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JUL
19
Today
Physics Department Summer Lectures
"Introduction to Statistics in High-Energy Physics"
Presented by Xin Qian
12:30 pm, Small Seminar Room, Bldg. 510
Friday, July 19, 2019, 12:30 pm
Hosted by: Mary Bishai
In this lecture, I will introduce some basic statistical concepts commonly used in the data analysis of high-energy physics experiments. I will review the basic procedure in setting confidence intervals. Some advanced topics in data unfolding, selection of test statistics, and usage of linear algebra in reducing computation will be touched upon.
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JUL
22
Monday
Condensed-Matter Physics & Materials Science Seminar
"Electron beam effects on organic ices"
Presented by Marco Beleggia, Technical University of Denmark, Denmark
11 am, ISB Bldg. 734 Conf. Rm. 201 (upstairs)
Monday, July 22, 2019, 11:00 am
Hosted by: Yimei Zhu
While beam damage is often considered detrimental to our quantitative imaging capabilities, the energy and charge injected into the sample as a result of inelastic scattering can be exploited beneficially. This is especially true in radiation-chemistry-type experimental setups in the electron microscope where the beam promotes local wanted chemical reactions. We have observed that by exposing to the electron beam a layer of small volatile organic molecules condensed over a cold substrate results in the formation of a solid product. Evidence suggests that the exposure mechanism driving the formation of a solid product is partial dehydrogenation of the molecules, removal of H2, and progressive increase of the average molecular weight. Contrary to focused electron beam induced deposition, that relies on surface absorption followed by aggregation of mobile species, at cryogenic temperature organic ice molecules are largely immobilized, and act as targets for the incoming electrons throughout the entire thickness of the layer. Therefore, the exposure occurs throughout the volume of the frozen precursor, and the features are essentially determined by the electron distribution, with diffusion/transport parameters bearing little or no relevance. Since larger molecules are less volatile, if the molecular weight increases sufficiently, upon raising the temperature the unexposed areas leave the sample, while the exposed molecules assemble into a solid product in the form of hydrogenated amorphous carbon.
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JUL
23
Tuesday
Physics Department Summer Lectures
"Searching for and understanding the quark-gluon plasma in heavy-ion"
Presented by Rongrong Ma, BNL
12:30 pm, Small Seminar Room, Bldg. 510
Tuesday, July 23, 2019, 12:30 pm
Hosted by: Mary Bishai
Lattice-QCD predicts the occurrence of a phase transition above a critical temperature from ordinary nuclear matter to a new state of matter, usually referred to as the quark-gluon plasma (QGP), in which partons are relevant degrees of freedom. One primary goal of the heavy-ion physics is to create and study the properties of the QGP created in these collisions. The last couple of decades have seen tremendous progresses in understanding the QGP, thanks to the successful operation of dedicated experiments at the RHIC and the LHC. In this lecture, I will discuss the detectors designed for heavy-ion physics, and how an experimentalist turns electronic signal into physics results. Future direction of heavy-ion experiments will also be discussed.
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JUL
25
Thursday
Sambamurti Lecture
"Finger-printing a nuclear reactor with neutrinos"
Presented by Thomas Langford, Yale University
3:30 pm, Large Seminar Room, Bldg. 510
Thursday, July 25, 2019, 3:30 pm
Hosted by: John Haggerty
Neutrinos have been the most consistently surprising particle of the last few decades. The onset of high-precision experiments has lead to the discovery of neutrino oscillations, possible evidence for beyond the Standard Model sterile neutrinos, and the beginnings of neutrino-based geophysics. Recent measurements of antineutrinos from nuclear reactors have observed flux and spectral discrepancies compared to leading theoretical models. Experiments like Daya Bay and PROSPECT are able to observe the small differences of neutrino emission from different mixtures of nuclear fuel, which may illuminate the origin of this disagreement. These neutrino finger-prints can also be used to investigate the mixture of fuel inside an operating reactor, rekindling interest in neutrino-based reactor monitoring. I will present recent advances which have demonstrated how small-scale experiments utilizing new technologies can advance both fundamental and applied science.
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JUL
26
Friday
Condensed-Matter Physics & Materials Science Seminar
"Fermi arcs, nodal and antinodal gaps in cuprates : the 'pairon' model to the rescue"
Presented by William Sacks, Sorbonne University, France
1:30 pm, ISB Bldg. 734 Conf. Rm. 201 (upstairs)
Friday, July 26, 2019, 1:30 pm
Hosted by: Ivan Bozovic
Angle-resolved photoemission, in addition to tunneling, has provided key information on the cuprate pairing on the microscopic scale. In particular, in the underdoped regime, the angular dependence of the gap function Δ(θ) deviates from a pure d-wave form such that the antinodal gap value ΔAN and the nodal gap value ΔN completely diverge. On another front, ARPES has firmly established that the enigmatic Fermi arcs, i.e. normal electron excitations around the nodes, exist even below Tc. In this work, we will interpret these experiments based on the 'pairon' model [1] in which the fundamental object is a hole pair bound by its local antiferromagnetic environment on the scale of the coherence length ξAF. The pairon model agrees quantitatively with both the gap function Δ(θ) and the Fermi arcs seen at finite temperature.
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Physics Department Summer Lecture Series
"Quantum Chromodynamics (QCD) as a many-body theory: An existential tale in four acts"
Presented by Raju Venugopalan, BNL
Tuesday, July 16, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
QCD, our nearly perfect theory of the strong interaction, is also deeply profound because all phenomena are emergent features of the many-body dynamics of the quark and gluon fields and the vacuum of the theory. This talk on many-body QCD is organized as a play in four acts: i) Origins, mysteries, symmetries ii) The power and the glory of QCD iii) Surprises from boiling the QCD vacuum in heavy-ion collisions: a) why the world's hottest fluid, albeit also being its most viscous, flows with almost no resistance b) a possible unexpected universality between the hottest and coldest fluids on earth c) What magnetar strength magnetic fields created in heavy-ion collisions may reveal about the topology of the QCD vacuum iv) Looking ahead to the Electron-Ion Collider: what the ultimate IMAX experience may reveal of QCD's mysteries
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Chemistry Department Seminar
"Nanoparticle Beam Deposition: A Novel Route to the Solvent-Free"
Presented by Richard E. Palmer, Nanomaterials Lab, Swansea University, UK, United Kingdom
Tuesday, July 16, 2019, 11 am
Room 300, 3rd Floor, Chemistry Building 555Hosted by: Michael White
Size-selected nanoparticles (atomic clusters), deposited onto supports from the beam in the absence of solvents, represent a new class of model systems for catalysis research and possibly small-scale manufacturing of selective catalysts. To translate these novel and well-controlled systems into practical use, two major challenges have to be addressed. (1) Very rarely have the actual structures of clusters been obtained from direct experimental measurements, so the metrology of these new material systems have to improve. The availability of aberration-corrected HAADF STEM is transforming our approach to this structure challenge [1,2]. I will address the atomic structures of size-selected Au clusters, deposited onto standard carbon TEM supports from a mass-selected cluster beam source. Specific examples considered are the "magic number clusters" Au20, Au55, Au309, Au561, and Au923. The results expose, for example, the metastability of frequently observed structures, the nature of equilibrium amongst competing isomers, and the cluster surface and core melting points as a function of size. The cluster beam approach is applicable to more complex nanoparticles too, such as oxides and sulphides [3]. (2) A second major challenge is scale-up, needed to enable the beautiful physics and chemistry of clusters to be exploited in applications, notably catalysis [4]. Compared with the (powerful) colloidal route, the nanocluster beam approach [5] involves no solvents and no ligands, while particles can be size selected by a mass filter, and alloys with challenging combinations of metals can readily be produced. However, the cluster approach has been held back by extremely low rates of particle production, only 1 microgram per hour, sufficient for surface science studies but well below what is desirable even for research-level realistic reaction studies. In an effort to address this scale-up challenge, I will discuss the development of a new kind of nanop
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NT/RIKEN Seminar
"Topological Superconducting Qubits"
Presented by Javad Shabani, Center for Quantum Phenomena NYU
Friday, July 12, 2019, 2 pm
Building 510, CFNS Room 2-38Hosted by: Niklas Mueller
Topological superconductivity hosts exotic quasi-particle excitations including Majorana bound states which hold promise for fault-tolerant quantum computing. The theory predicts emergence of Majorana bound states is accompanied by a topological phase transition. We show experimentally in epitaxial Al/InAs Josephson junctions a transition between trivial and topological superconductivity. We observe a minimum of the critical current at the topological transition, indicating a closing and reopening of the superconducting gap induced in InAs, with increasing magnetic field. By embedding the Josephson junction in a phase-sensitive loop geometry, we measure a π-jump in the superconducting phase across the junction when the system is driven through the topological transition. We present a scalable topological qubit architecture to study coherence for computing applications. Funded by DARPA TEE program.
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Physics Department Summer Lecture Series
"A golden age in physics, an overview of what the...is going on in the RHIC tunnel"
Presented by Rob Pisarski, BNL
Friday, July 12, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
I will give a general introduction to the modern theory of "strong" interactions, which involve quarks and gluons. At about a trillion degrees, these form a Quark-Gluon Plasma, which we believe is created in the collisions of heavy ions at very high energies, such as at the Relativistic Heavy Ion Collider here at Brookhaven. I also make extensive comments about the sociology of the field, especially the phenomenon of "As everyone who is anyone knows..."
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Particle Physics Seminar
"Low-nu Flux Measurement Using Neutrino/Antineutrino-Hydrogen Interactions for Long-baseline Neutrino Oscillation Experiments"
Presented by Hongyue Duyang, University of South Carolina
Thursday, July 11, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
The next generation long-baseline neutrino oscillation experiments such as DUNE (Deep Underground Neutrino Experiment) aim to solve the remaining questions in neutrino oscillation physics, including neutrinos' mass ordering and CP violation. The near detector(s) will provide crucial constraints on the systematic uncertainties to the oscillation measurements. Flux uncertainty is one of the dominant contributions to the systematic uncertainties. In this talk I present a novel approach of precisely determining the neutrino flux in the near detector(s) of a long-baseline neutrino experiment such as DUNE, by using neutrino/antineutrino-hydrogen interactions with low visible hadronic energy (Low-nu). The application of this method in the proposed KLOE-STT detector is discussed, which could serve as part of the near detector complex of DUNE.
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Physics Department Summer Lecture Series
"Silicon Detectors for Particle and Nuclear Physics"
Presented by Gabriele Giacomini, BNL
Tuesday, July 9, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
Silicon technology is approximately 70 years old but thousands of years by a multitude of researchers has been dedicated to R&D; the well-established microelectronic industry is based on it. Being that the silicon is sensitive to photons (from infrared to X-rays, passing through visible light and ultraviolet) and to charged particles, we can leverage the microelectronic technology to make sensors out of silicon. Silicon sensors are used in a variety of applications including scientific experiments (High Energy Physics, Astrophysics, Photon Science, etc) as well as industrial and commercial use (cameras, etc). The basic structure is the p-n junction across which a voltage is applied. When an ionizing event occurs (a photon or a charged-particle interacting with silicon), a short current pulse (~ few ns) is generated and detected by the read-out electronics. There are many kinds of silicon sensors and each one must be tailored according to the specific application. We'll give an overview of the state of the silicon technology and its different applications.
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Nuclear Physics Seminar
": Extracting the Heavy-Quark Potential from Bottomonium Observables in Heavy-Ion Collisions"
Presented by Xiaojian Du, Texas A&M University
Tuesday, July 9, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
The in-medium color potential is a fundamental quantity for understanding the properties of the strongly coupled quark-gluon plasma (sQGP). Open and hidden heavy-flavor (HF) production in ultrarelativistic heavy-ion collisions (URHICs) has been found to be a sensitive probe of this potential. Here we utilize a previously developed quarkonium transport approach in combination with insights from open HF diffusion to extract the color-singlet potential from experimental results on Υ production in URHICs. Starting from a parameterized trial potential, we evaluate the Υ transport parameters and conduct systematic fits to available data for the centrality dependence of ground and excited states at RHIC and the LHC. The best fits and their statistical significance are converted into a temperature dependent potential. Including nonperturbative effects in the dissociation rate guided from open HF phenomenology, we extract a rather strongly coupled potential with substantial remnants of the long-range confining force in the QGP.
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Physics Department Summer Lecture Series
"Astronomical CCDs and light-sensitive sensors for fast imaging"
Presented by Andrei Nomerotski, BNL
Tuesday, July 2, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
I will review how the state-of-the-art sensors developed for astronomical applications can precisely measure the positions and shapes of billions of galaxies. The talk will focus on the camera and sensors for the Large Synoptic Survey Telescope (LSST) and will discuss limitations on the achievable precision coming from the instrumentation. I will also discuss light sensitive sensors which can be used for fast imaging of single photons in QIS and other applications.
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Nuclear Physics Seminar
"DREENA framework as a multipurpose QGP tomography tool"
Presented by Magdalena Djordjevic, Institute of Physics Belgrade
Tuesday, July 2, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
High-pt theory and data are traditionally used to explore high-pt parton interactions with QGP, while QGP bulk properties are explored through low-pt data and corresponding models. However, with a proper description of high-pt medium interactions, high-pt probes also become a powerful tool for inferring bulk QGP properties, as they are sensitive to global QGP parameters. With the goal of developing a multipurpose QGP tomography tool, over the past several years, we developed the dynamical energy loss formalism, and the corresponding fully optimized DREENA numerical framework. As first steps towards QGP tomography, we will use DREENA framework to address how we can directly from experimental data i) differentiate between different energy loss mechanisms, ii) infer the shape of QGP droplet. The research presented in this talk will therefore demonstrate how high-pt theory and data can be used to both infer the nature of high pt-parton medium interactions, and important bulk QGP medium properties.
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Nuclear Physics Seminar
"Charm hadron collective flow and charm hadrochemistry in heavy-ion collisions"
Presented by Xin Dong, Lawrence Berkeley National Laboratory
Tuesday, July 2, 2019, 10 am
Small Seminar Room, Bldg. 510Hosted by: Lijuan Ruan
Heavy quark transport offers unique insight into the microscopic picture of the sQGP created in heavy-ion collisions. One central focus of heavy quark program is to determine the heavy quark spatial diffusion coefficient and its momentum and temperature dependence. This requires precise measurements of heavy flavor hadron production and their collective flow over a broad momentum region. In the meantime, heavy quark hadrochemistry, the abundance of various heavy flavor hadrons, provides special sensitivity to the QCD hadronization and also plays an important role for the interpretation of heavy flavor hadron data in order to constrain the heavy quark spatial diffusion coefficient of the sQGP. In this seminar, I will focus on the recent STAR results of charm hadron D0, D+/-, D*, Ds, Lambda_c production and D0 radial and elliptic flow in heavy-ion collisions utilizing the state-of-the-art silicon pixel detector, the Heavy Flavor Tracker. These data will be compared to measurements from other experiments at RHIC and the LHC as well as various model calculations. I will then discuss how these data will help us better understand the sQGP properties and its hadronization. Finally, I will present a personal view of future heavy quark measurements at RHIC.
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Particle Physics Seminar
"Searches of Dark Matter signals with the ATLAS detector at the LHC: Present and future"
Presented by Dr. Rachid Mazini, Academia Sinica, Taiwan
Monday, July 1, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
In this seminar, I will present an overview of up-to-date results on searches for Dark Matter signals with the ATLAS detector at the LHC using Run 2 data. Comparison with non-accelerator DM results as well as interpretation within some theoretical models will be discussed. In addition, expectation from the high-luminosity LHC (HL-LHC) DM searches program will be briefly presented. Finally, I will talk about the new ATLAS High Granularity Timing Detector (HGTD), planned for the phase 2 upgrade program for the HL-LHC run, and it performances for physics studies.
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Physics Department Summer Lecture Series
"Using Gravitational Lensing to measure Dark Matter and Dark Energy in the Universe"
Presented by Erin Sheldon, BNL
Friday, June 28, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
Gravitational lensing is the bending of the path of light near massive bodies. Mass produces a curvature of space time, and light follows a curved path that is calculable using the General Theory of Relativity. I will discuss how the lensing effect is used to measure the amount of Dark Matter in galaxies and in the universe as a whole. I will also discuss how we use lensing to measure the properties of the mysterious Dark Energy that is driving the accelerated expansion of our universe.
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Particle Physics Seminar
"First measurement of the neutron-argon cross section between 100 and 800 MeV"
Presented by Prof. Christopher Mauger, University of Pennsylvania
Thursday, June 27, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
The DUNE experiment directs a neutrino beam from Fermilab towards a 40 kiloton liquid argon time-projection chamber (TPC) 1300 km away in the Sanford Underground Research Facility in South Dakota. By measuring electron neutrino and anti-neutrino appearance from the predominantly muon neutrino and anti-neutrino beams, DUNE will determine the neutrino mass ordering and explore leptonic CP violation. The neutrino oscillation phenomena explored by DUNE require robust determinations of the (anti-)neutrino energies by reconstructing the particles produced in charged current reactions. Among the particles emerging from the interaction which carry significant energy, neutrons are the most challenging to reconstruct. The CAPTAIN collaboration has made the first measurement of the neutrino-argon cross section between 100 and 800 MeV of neutron kinetic energy - an energy regime crucial for neutrino energy reconstruction at DUNE. We made the measurement in a liquid argon TPC with 400 kg of instrumented mass. I describe the measurement and discuss future plans.
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HET Seminar
"Inducing and Detecting Collective Effects of Particle Dark Matter"
Presented by Asher Berlin, SLAC
Wednesday, June 26, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Gopolang Mohlabeng
Detecting light dark matter that interacts weakly with electromagnetism has recently become one of the benchmark goals of near-term and futuristic direct detection experiments. In this talk, I will discuss an alternative approach to directly detecting such models below the GeV-scale, leveraging on the recent interest and advances in resonant detectors, such as LC circuits.
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Condensed-Matter Physics & Materials Science Seminar
"Excitonic condensation of strongly correlated electrons"
Presented by Professor Jan Kunes, Vienna University of Technology, Austria
Wednesday, June 26, 2019, 2:30 pm
Bldg. 734, ISB Conference Room 201 (upstairs)Hosted by: Keith Gilmore
Spontaneous symmetry breaking is a prominent demonstration of the collective behavior of strongly correlated systems. Besides ordering of charge or of spin dipoles, more exotic types of long-range order are possible, which do not couple to conventional probes and are therefore sometimes called the hidden order. Excitonic magnets, or excitonic condensates, are examples of such systems. I will introduce the concept of excitonic condensate from the strong coupling perspective and discuss the rich variety of excitonic phases arising from the internal (spin, orbital) degrees of freedom of the excitons. I will present some numerical results obtained with dynamical mean-field theory for models as well as for specific materials, which we suspect to be excitonic magnets. The presentation will include the recently obtained results for dynamical susceptibilities in phases with long-range order and some proposals on how to detect excitonic condensates with today's experimental techniques.
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Physics Department Summer Lecture Series
"Search for a new particle in the decay of the Higgs boson"
Presented by Ketevi Assamagan, BNL
Friday, June 21, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
In this talk, I will discuss the search strategies that led to the discovery of the Higgs boson. Then, I will focus on the usage of the Higgs boson as a portal to "new physics". I will conclude with dark sector states as a possibility for physics beyond the Standard Model of particle physics
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Physics Department Summer Lecture Series
"Basics of Neutrino Interactions in Matter"
Presented by Milind Diwan, BNL
Tuesday, June 18, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
I will review the basics of neutrino interactions in matter with emphasis on calculations of cross sections and rates. The lecture will provide introduction to the physics of weak interactions.
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Nuclear Physics Seminar
"First observation of the directed flow of D0 and anti-D0 in Au+Au collisions at sqrt(sNN) = 200 GeV"
Presented by Subhash Singha, KSU
Tuesday, June 18, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Isaac Upsal
In this talk, we will present the first measurement of rapidity-odd directed flow (v1) for D0 and anti-D0 mesons at mid-rapidity (|y| < 0.8) in Au+Au collisions at sqrt(sNN) = 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10-80% Au+Au collisions, the slope of the v1 rapidity dependence (dv1/dy), averaged over D0 and anti-D0 mesons, is -0.080 +/- 0.017 (stat.) +/- 0.016 (syst.) for transverse momentum (pT) above 1.5 GeV/c. The absolute value of D0-meson dv1/dy is about 25 times larger than that for charged kaons, with 3.4sigma significance. These data not only give unique insight into the initial tilt of the produced matter, they are expected to provide improved constraints for the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.
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Condensed-Matter Physics & Materials Science Seminar
"Tracking phase textures in complex oxides using coherent x-rays"
Presented by Xiaoqian Chen, Lawrence Berkeley Laboratory
Monday, June 17, 2019, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson/Mark Dean
In complex oxides, coupled interactions result in unpredictable and novel emerging orders that are yet to be understood. With the recent advancement in x-ray and laser sources, exploration of equilibrium fluctuation and nonlinear dynamics have become an effective approach to understand these intertwined orders. In particular, coherent x-rays are a simultaneous probe of the order parameter, phase texture, and dynamics. In the first part of my talk, I will use underdoped cuprate La2-xBaxCuO4 as an example to show how x-ray speckle correlation can be a test for (lattice degree of freedom and charge) order coupling and dynamics. However, can we image domain dynamics in real time? In the second part of my talk, I will use antiferromagnetically ordered artificial lattice to demonstrate that phase retrieval lensless imaging can be used to image charge and magnetic orders. Using Bragg coherent diffraction imaging, we revealed a single domain wall motion with 100ms time resolution. References [1] X. M. Chen et al. Phys. Rev. Lett. 117, 167001 (2016) [2] V. Thampy et al. Phys. Rev. B 95, 241111 (2017) [3] X. M. Chen et al. Nat Commun. 10 1435 (2019) [4] X. M. Chen et al. under review, arXiv:1809.05656 [cond-mat.mes-hall]
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NT/RIKEN Seminar
"D meson mixing via dispersion relation"
Presented by Hsiang-nan Li, National Center for Theoretical Sciences, Physics Division, Taiwan
Friday, June 14, 2019, 2 pm
Building 510, CFNS Room 2-38Hosted by: Niklas Mueller
In this talk I will explain how to calculate the D meson mixing parameters x and y in the Standard Model. Charm physics is notoriously difficult, because most effective theories and perturbation theories do not apply well. I propose to study the D meson mixing via a dispersion relation, which relates low mass dynamics to high mass one. Taking heavy quark results as inputs in the high mass region, we obtain x and y consistent with experimental data at least in order of magnitude.
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Physics Department Summer Lecture Series
"The Little Neutral One"
Presented by Mary Bishai, BNL
Friday, June 14, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
In the past 50 years, the study of neutrinos, the lightest, yet most abundant of the known elementary particles has revealed cracks in the Standard Model of Particle Physics. Could neutrinos explain the matter anti-matter asymmetry in our Universe? To answer these questions we need to better understand the properties of these elusive polymorphs. I will present a brief history of the neutrino, what we have learnt so far about it, and what we hope to learn in the next couple of decades from some of the most ambitious experiments in particle physics.
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NSLS-II Friday Lunchtime Seminar
"High resolution strain measurements and phase discrimination in solid solutions using X-Ray Diffuse Multiple Scattering (DMS)"
Presented by Gareth Nisbet, Diamond Light Source, United Kingdom
Friday, June 14, 2019, 12 pm
NSLS-II Bldg. 743 Room 156Hosted by: Ignace Jarrige
DMS is a new high resolution scattering technique which manifests as diffraction lines impinging on the detector plane, similar to Kikuchi lines or Kossel lines. I will explain how multiple intersections from coplanar and non-coplanar reflections can be used for phase discrimination in multi-phasic systems by following a simple reductive procedure. The methods will be demonstrated using data from complex PMN-PT and PIN-PMN-PT ferroelectric solid solutions. I will also show how convolutional neural networks are being applied to DMS data for phase discrimination.
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Particle Physics Seminar
"Argon Capture Experiment at DANCE (ACED)"
Presented by Jingbo Wang, UC Davis
Thursday, June 13, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
Liquid argon is becoming a popular medium for particle detection, with applications ranging from low-background dark matter searches to high-energy neutrino detection. Because neutrons may represent both an important source of background and a product of signal events, a good understanding of their interactions in argon is a requirement for precision physics measurements. Despite being one of the most basic quantities needed to describe low energy neutron transport, the thermal neutron capture cross section on argon remains poorly understood, with the existing activation measurements showing significant disagreements. To resolve these disagreements, the Argon Capture Experiment at DANCE (ACED) collaboration has performed a differential measurement of the 40Ar(n, gamma)41Ar cross section using a time of flight neutron beam and the Detector for Advanced Neutron Capture Experiments (DANCE), a ∼4pi gamma spectrometer at Los Alamos National Laboratory. A fit to the differential cross section from 0.015-0.15eV, assuming a 1/v energy dependence, yields sigma(2200)=673+-26 (stat.) +- 59(sys.) mb. During this talk, I will introduce the DUNE experiment before focusing on the importance of neutrons in liquid argon detectors. I will then present the ACED experiment and the use of neutrons as a detector calibration method.
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Physics Colloquium
"High energy atmospheric neutrinos: connections between laboratory experiments and cosmic rays"
Presented by Mary Hall Reno, University of Iowa
Tuesday, June 11, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Milind Diwan
The IceCube Neutrino Observatory's measurement of a diffuse flux of neutrinos from astrophysical sources has opened a new era in high energy astroparticle physics. Neutrinos produced by cosmic ray interactions in the atmosphere are the main background to the astrophysical neutrino flux. At these high energies, data from the Large Hadron Collider experiments on heavy flavor production can be used to narrow the uncertainties in the background predictions at the highest energies. Our evaluation of the atmospheric neutrino flux from charm will be used to illustrate how collider physics results are connected to cosmic ray physics in this context.
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Physics Department Summer Lecture Series
"The Anomalous Magnetic Moment of the Muon and the Standard Model of Particle Physics"
Presented by William Morse, BNL
Tuesday, June 11, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
At the end of this lecture, you will know: What is anomalous about the magnetic moment of the muon. What is the magnetic moment of the muon. What is the muon. Why Bohr said "Anyone who thinks they understand Quantum Mechanics, and is not deeply disturbed by it, doesn't understand Quantum Mechanics." What the Standard Model Theorists have to fear from the anomalous magnetic moment of the muon.
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Physics Department Summer Lecture Series
"Visible and Invisible Clues for New Physics"
Presented by Hooman Davoudiasl, BNL
Friday, June 7, 2019, 12:30 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
In this presentation, we will briefly describe the main elements of the Standard Model of particle physics. This theory, together with General Relativity, provides a precise description of a vast array of experimental and observational data, from microscopic to astronomical scales. However, solid empirical evidence and conceptual clues lead us to expect that this "standard" picture is incomplete. We will discuss some of the key reasons for this expectation.
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NSLS-II Friday Lunchtime Seminar
"Status and perspective of high-energy automotive batteries"
Presented by Richard Schmuch, University of Munster, Germany
Friday, June 7, 2019, 12:30 pm
NSLS-II Bldg. 743 Room 156Hosted by: Ignace Jarrige
This presentation gives an overview of the materials, performance requirements and cost of current automotive traction batteries based on Li-ion technology. It also includes important aspects related to electromobility, such as its sustainability and energy efficiency. As current Li-Ion batteries with intercalation-type active materials are approaching their physicochemical energy density limit of roughly 300 Wh/kg or 800 Wh/L, alternative technologies such as lithium-metal based all-solid-state batteries (ASSBs) currently intensively studied, which promise an energy density of up to 1000 Wh/L. The potential and challenges of this and other post Li-ion batteries (e.g. Dual-Ion, Mg-Ion, Li-Sulphur) are discussed and also compared by systematic bottom-up energy density calculations. Through a step-by-step analysis from theoretical energy content at the material level to practical energies at the cell level, the individual advantages and shortcomings of the studied battery types are elucidated. Literature: (1) Schmuch, R.; Wagner, R.; Hörpel, G.; Placke, T.; Winter, M. Performance and Cost of Materials for Lithium-Based Rechargeable Automotive Batteries. Nat. Energy 2018, 3 (4), 267–278. (2) Betz, J.; Bieker, G.; Meister, P.; Placke, T.; Winter, M.; Schmuch, R. Theoretical versus Practical Energy: A Plea for More Transparency in the Energy Calculation of Different Rechargeable Battery Systems. Adv. Energy Mater. 2018, 1803170, 1803170. (3) Placke, T.; Kloepsch, R.; Dühnen, S.; Winter, M. Lithium Ion, Lithium Metal, and Alternative Rechargeable Battery Technologies: The Odyssey for High Energy Density. J. Solid State Electrochem. 2017, 1–26. (4) Meister, P.; Jia, H.; Li, J.; Kloepsch, R.; Winter, M.; Placke, T. Best Practice: Performance and Cost Evaluation of Lithium Ion Battery Active Materials with Special Emphasis on Energy Efficiency. Chem. Mater. 2016, 28 (20), 7203-7217
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Condensed-Matter Physics & Materials Science Seminar
"Probing quantum materials with multiple spectroscopic techniques"
Presented by Eduardo H. da Silva Neto, University of California, Davis
Thursday, June 6, 2019, 1:30 pm
ISB - Bldg. 734Hosted by: Robert Konik
Resonant X-ray Scattering (RXS), Scanning Tunneling Spectroscopy (STS) and Angle-Resolved Photo-Emission Spectroscopy (ARPES) measurements have been at the forefront of several advances in the studies of quantum materials. Our group specializes in these techniques, looking to leverage their combination to the study of quantum materials. I will discuss two projects where we have used these state-of-the-art techniques to study high-temperature superconductors and topological materials. Charge order has now been ubiquitously observed in cuprate high-temperature superconductors. However, it remains unclear if the charge order is purely static or whether it also features dynamic correlations. I will discuss a polarization-resolved soft x-ray inelastic RXS experiment with unprecedented resolution that demonstrates the existence of a coupling between dynamic magnetic and charge-order correlations in the electron-doped cuprate Nd2−xCexCuO4 [1-3]. I will also discuss a combined ARPES-STS study of the topological material Hf2Te2P. Similar to the reports by H. Ji, et al. on Zr2Te2P [4], band structure calculations and ARPES by Hosen et al. [5] also suggest multiple topological surface states in Hf2Te2P. However, some topological surface states still lacked direct spectroscopic evidence due the inability of ARPES experiments to probe the unoccupied band structure. Using the combination of STS and ARPES with surface K-doping, we probe the unoccupied band structure of Hf2Te2P and demonstrate the presence of multiple surface states with a linear Dirac-like dispersion, consistent with the predictions from previously reported band structure calculations [6]. [1] E. H. da Silva Neto, et al. Science 347, 282 (2015). [2] E. H. da Silva Neto, et al. Science Advances 2 (8), e1600782 (2016). [3] E. H. da Silva Neto, et al. Physical Review B, Rapid Communication 98, 161114(R) (2018). [4] H. Ji, et al. Physical
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Condensed-Matter Physics & Materials Science Seminar
"Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory"
Presented by Xiaozhe Shen, SLAC National Accelerator Laboratory
Monday, June 3, 2019, 2 pm
Bldg. 480, Conference RoomHosted by: Jing Tao
Ultrafast electron diffraction (UED) is a transformative tool for probing atomic structural dynamics in ultrafast science to understand the correlation between materials' structure and their functionalities, with the ultimate goal of controlling energy and matter. The advent of high-brightness relativistic electron beams from photocathode radio frequency (RF) gun provides a great opportunity to push the resolving power of UED onto atomic length and time scales. With the expertise in electron beam physics and ultrafast laser technology, SLAC has dedicated enormous efforts to develop a world-leading UED using mega-electron-volt (MeV) electron beams since 2014. Over the years, SLAC MeV UED has achieved great instrument performance and delivered numerous scientific outcomes for ultrafast science. In 2019, SLAC MeV UED has officially transformed into a user facility. In this talk, performance of SLAC MeV UED will be reviewed, including characterization of the instrument resolution and machine stability. The unique capabilities of SLAC MeV UED to accommodate various sample environments for a broad range of scientific interests, including condense matter physics and chemical science, will be presented, with highlighted scientific results. Research and development efforts to improve the performance of SLAC MeV UED will be discussed.
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Particle Physics Seminar
"Dark matter in the cosmos-The Hunt to Find it in the Laboratory"
Presented by Ioannis (J.D.) Vergados
Friday, May 31, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Milind Diwan
There is plenty of evidence at all scales (galaxies, cluster of galaxies, cosmological distances) that most of the energy content of the universe is of unknown nature, i.e, 70% is dark energy and 25% dark matter. Only 5% is made up of matter of known nature, in atoms, in stars, in planets etc, constituents predicted by the standard model. Thus unraveling the nature of the dominant components and, in particular, of dark matter is one of the most important open problems in science. This nature can only be understood by the direct detection of its constituents in the laboratory. This can be achieved, if there exists a week interaction, much stronger than gravity, between the dark matter and ordinary matter. The constituents are supposed to have a mass and are called WIMPs (weakly interacting massive particles). We have no idea what this mass is, but from the rotational curves we know that the constituents must be non relativistic, regardless of the size of their mass. The experimental techniques for the direct detection crucially depend on the assumed WIMP mass. Historically the first searches assumed WIMP masses of many GeV and, therefore, heavy nuclear targets were favored. Thus the hunt for DM began and evolved into a multi-pronged and interdisciplinary enterprise, combining cosmology and astrophysics, particle and nuclear physics as well as detector technology, which will be reviewed. Since the WIMP energy is in the keV region, the nucleus cannot be excited and only the nuclear recoil can be measured. As a result, unfortunately, the signal cannot be easily distinguished from backgrounds. After thirty years of intensive work against formidable backgrounds by a lot of large experimental teams, no dark matter has been found. Impressive limits on the nucleon cross section have, however, been obtained. Extension of these searches to GeV or sub-GeV WIMPs is also been considered using light nuclear targets. It may very w
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Particle Physics Seminar
"Latest oscillation results from the NOvA experiment"
Presented by Diana Patricia Mendez, University of Sussex
Thursday, May 30, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Elizabeth Worcester
NOvA is a long-baseline neutrino oscillation experiment measuring $\nu_{\mu}$ disappearance and $\nu_e$ appearance within the NuMI beam from Fermilab. The experiment uses a Near and a Far Detector placed 810 km away from each other and at 14 milliradians off the beam-axis resulting in an observed energy spectrum that peaks at 2 GeV, close to the oscillation maximum. A combined $\bar{\nu}_{\mu}$ + $\nu_{\mu}$ disappearance, and $\bar{\nu}_{e}$ + $\nu_{e}$ appearance result will be presented including NOvA's first collected anti-neutrino data for a total exposure of $16\times10^{20}$ protons-on-target. In addition to an increased exposure, an upgraded analysis has enable the experiment to set new limits to the allowed regions for $\Delta m^2_{32}$ and sin$^2\theta_{23}$ and make a measurement of $\Delta m^2_{32}$ among the world's best.
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RIKEN Lunch Seminar
"Applications of machine learning to computational physics"
Presented by Dr Akio Tomiya, RBRC
Thursday, May 30, 2019, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
In this talk, I would like to talk about my works with machine learning. I plan to introduce my works which related to lattice QCD research: detection of phase transition in classical spin systems [arXiv 1609.09087, 1812.01522], configuration generation [1712.03893 + some]
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Environmental & Climate Sciences Department Seminar
"The Influence of Aerosol Chemical Composition, Morphology, and Phase State on Water and Ice Cloud Particle Formation"
Presented by Yue Zhang, North Carolina State, MIT, and Aerodyne
Thursday, May 30, 2019, 11 am
Large Conference Room, Bldg. 490Hosted by: Ernie Lewis
Aerosols and clouds effect Earth's radiative balance, and aerosol-cloud interactions are major sources of uncertainties in predicting future climate. The climate effects of water and ice cloud particles formed from atmospheric particulate matter are not well understood due to the complex physical and chemical properties of these aerosols. Measurements from fixed sites and field campaigns have shown that organic aerosols (OA) dominate the non-refractory aerosols in the free troposphere where clouds typically form, and cloud water and ice cloud residue both show the presence of organic materials. Despite the abundance of OA, their effects on both cloud condensation nuclei (CCN) and ice nucleation (IN) are not fully understood and even controversial. To probe into these issues, the CCN and IN properties of complex inorganic-organic aerosol mixtures that simulate ambient conditions were measured with a cloud condensation nuclei counter (CCNC, DMT, Inc.) and a spectrometer for ice nucleation (SPIN, DMT, Inc.) at a variety of laboratory conditions. Our studies suggest that the composition of the organic-containing aerosols, as well as their morphology and phase state, jointly impact their cloud forming potential. The results highlight the importance of combining aerosol physical and chemical properties to accurately understand cloud particle formation processes and their implications on the climate.
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Nuclear Physics Seminar
"Examining hydrodynamical modelling of the QGP through dilepton radiation"
Presented by Gojko Vujanovic, Wayne State University
Tuesday, May 28, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
Recent viscous hydrodynamical studies at the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC), show that bulk viscosity plays an important role in their phenomenological description. A temperature-dependent bulk viscosity in the hydrodynamical evolution of the medium can modify the development of the hydrodynamic momentum anisotropy differently in the high- and low-temperature regions. Thus, anisotropic flow coefficients of various particle species are affected differently depending where their surface of last scattering lies. For the case of hadronic observables, they are predominantly sensitive to low temperature regions, while electromagnetic radiation is emitted at all temperatures. Therefore, bulk viscosity should affect electromagnetic radiation differently than hadron emission. The effects of bulk viscosity on one of the electromagnetic probes, namely photons, has already been investigated. The same statement holds true for hadrons. The goal of this presentation is to study how dilepton production, the other source of electromagnetic radiation, gets modified owing to the presence of bulk viscosity at RHIC and LHC energies. With calculations at different collision energies, comparisons in the dilepton signal can be made and more robust conclusions regarding the role of bulk viscosity in high energy heavy-ion collisions can be drawn. Dilepton radiation from the dilute hadronic sector of the medium, which are radiated in addition to dileptons emitted during the hydrodynamical evolution, will also be included to ascertain whether interesting dynamics induced by bulk viscosity may have observable consequences. To complete that investigation, particular attention will be given to how the $\rho(770)$ meson, and its subsequent dilepton decay, is calculated at the end of the hydrodynamical simulation.
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NT/RIKEN Seminar
"Pieces of the Puzzle: Reaching QCD on Quantum Computers"
Presented by Henry Lamm, UMD
Friday, May 24, 2019, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Niklas Mueller
The advent of quantum computing for scientific research presents the possibility of calculating time-dependent observables like viscosity and parton distributions from QCD. In order to utilize this new tool, a number of theoretical and practical issues must be addressed related to efficiently digitize, initialize, propagate, and evaluate quantum field theory. In this talk, I will discuss a number of projects being undertaken by the NuQS collaboration to realize calculations on NISQ era and beyond quantum computers.
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CFNS Seminar
"Effect of non-eikonal corrections on two particle correlations"
Presented by Tolga Altinoluk, National Centre for Nuclear Research, Warsaw, Poland
Thursday, May 23, 2019, 4 pm
Building 510, CFNS Room 2-38Hosted by: Andrey Tarasov
We will discuss the non-eikonal effects on gluon production in pA collisions that originate from the finite longitudinal width of the target. We will then consider the dilute target limit, and discuss the single and double inclusive gluon production cross section in pp collisions. We will show that non-eikonal corrections break the accidental symmetry of the CGC and give rise to non-vanishing odd azimuthal harmonics.
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Condensed-Matter Physics & Materials Science Seminar
"In situ imaging of gold nanocrystals during the CO oxidation reaction studied by Bragg Coherent Diffraction Imaging"
Presented by Ana Flavia Suzana, Brazilian Association of Synchrotron Light Technology-ABTLUS, Brazil
Thursday, May 23, 2019, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson
The fundamental aim of heterogeneous catalysis research is to understand mechanisms at the nanoparticle level, and then to design and synthesize catalysts with desired active sites. In this regard, the in situ/operando characterization of defects is crucial as they are preferential catalytic sites for the reaction occurrence. In this seminar I will talk about the main part of the work developed during my PhD: the investigation of the morphology and structure evolution of gold nano-catalysts supported on titanium dioxide. Those catalytic materials were evaluated for the model CO oxidation reaction, chosen for its environmental relevance and "simplicity" to be reproducible within our X-ray imaging study. We used the Bragg Coherent Diffraction Imaging technique to follow in situ the 3D morphology changes under catalytic reaction conditions. We correlated the 3D displacement field and strain distribution of the gold nanoparticles to the catalytic properties of the material. In particular, for a 120 nm gold nanoparticle, we quantified under working conditions the adsorbate-induced surface stress on the gold nanocrystal, which leads to restructuration and defects identified as a nanotwin network.
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RIKEN Lunch Seminar
"Complex saddle points of path integrals"
Presented by Semeon Valgushev, BNL
Thursday, May 23, 2019, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
In this talk, we discuss the physical role of complex saddle points of path integrals. In the first case study, we analyze saddle point structure of two-dimensional lattice gauge theory represented as Gross-Witten-Wadia unitary matrix model. We find that non-perturbative physics in the strong coupling phase can be understood in terms of new family of complex saddle points those properties are connected to resurgent structure of the 1/N expansion. In the second case study, we discuss the sign problem in fermionic systems at finite density and the possibility to alleviate it with the help of defomations of integration contour into complex space on the example of two-dimensional Hubbard model.
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Chemistry Department Seminar
"Designing Dopants to Shield Anion Electrostatics in Doped Conjugated Polymers to Obtain Highly Mobile and Delocalized Carriers"
Presented by Taylor Aubry, UCLA
Thursday, May 23, 2019, 11 am
Room 300, 3rd Floor - Chemistry Bldg. 555Hosted by: Matthew Bird
Doping conjugated polymers is an effective way to tune their electronic properties for thin-film electronics applications. Chemical doping of semiconducting polymers involves the introduction of a strong electron acceptor or donor molecule that can undergo charge transfer (CT) with the polymer. The CT reaction creates electrical carriers on the polymer chain (usually positive polarons a.k.a. holes) while the dopant molecules remain in the film as counterions. Undesirably, strong electrostatic attraction from the anions of most dopants will localize the polarons and reduce their mobility. We employ a new strategy utilizing substituted icosahedral dodecaborane (DDB) clusters as molecular dopants for conjugated polymers. DDBs provide a unique system in which the redox potential of the dopant can be rationally tuned via modification of the substituents without significant change to the size or shape of the dopant molecule. These clusters allow us to disentangle the effects of energetic offset on the production of free and trapped carriers in DDB-doped poly-3-hexylthiophene (P3HT) films. We find that by designing our cluster to have a high redox potential and steric protection of the core-localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained.1 P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with conventional small-molecule dopants such as 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ). The spectral shape of the IR-region absorption for our DDB-doped polymer film closely matches the calculated theoretical spectrum for the anion at infinite distance from the polaron.2 We therefore conclude that these DDB clusters are able to effectively spatially separate the counterion. Moreover, nearly all DDB-produced carriers are free, while it has been shown that small m
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C-AD Accelerator Physics Seminar
"High-Level Software Development for the CLARA FEL Test Facility"
Presented by Dr. James Jones, Daresbury Laboratory
Wednesday, May 22, 2019, 3 pm
Bldg. 911B, Second Floor, Large Conf. Rm., Rm. A2Hosted by: Steve Peggs
CLARA is a low-energy test facility for advanced FEL physics and beam-driven novel acceleration techniques. As part of the facility we have planned for an advanced integrated system for high-level software development and online-model based on C++ and python interfaces. An overview of the CLARA facility and recent experimental results will be presented along with a description and current status of the HLS middle-layer and online-model. Future plans for CLARA will also be presented.
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Nuclear Physics Seminar
"Future opportunities for a small-system scan at RHIC"
Presented by Jiangyong Jia
Tuesday, May 21, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
The observation of multi-particle azimuthal correlations in high-energy small-system collisions has led to intense debate on its physical origin between two competing theoretical scenarios: one based on initial-state intrinsic momentum anisotropy (ISM), the other based on final-state collective response to the collision geometry (FSM). To complement the previous scan of asymmetric collision systems (p+Au, d+Au and He+Au), we propose a scan of small symmetric collision systems at RHIC, such as C+C, O+O, Al+Al and Ar+Ar at sqrt{s_NN} = 0.2 TeV, to further disentangle contributions from these two scenarios. These symmetric small systems have the advantage of providing access to geometries driven by the average shape of the nuclear overlap, compared to fluctuation-dominant geometries in asymmetric systems. A transport model is employed to investigate the expected geometry response in the FSM scenario. Different trends of elliptic flow with increasing charge particle multiplicity are observed between symmetric and asymmetric systems, while triangular flow appears to show a similar behavior. Furthermore, a comparison of O+O collisions at sqrt{s_NN} = 0.2 TeV and at sqrt{s_NN} =2.76−7 TeV, as proposed at the LHC, provides a unique opportunity to disentangle the collision geometry effects at nucleon level from those arising from subnucleon fluctuations.
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NSLS-II Friday Lunchtime Seminar
"MAXPD: Multi-Anvil X-ray Powder Diffraction — COMPRES Partner User Program for High Pressure Studies at 28-ID-2-D"
Presented by Matthew L. Whitaker, Stony Brook University
Friday, May 17, 2019, 12 pm
NSLS-II Bldg. 743 Room 156Hosted by: Ignace Jarrige
MAXPD is the downstream endstation of XPD, an insertion device beamline at Sector 28 (28-ID-2-D) of NSLS-II. The MAXPD endstation and General User Program are sponsored by the COnsortium for Materials Properties Research in Earth Sciences (COMPRES). MAXPD has an 1100-ton hydraulic press installed, which is equipped with a unique DT-25 pressure module that can be swapped out for a more standard D-DIA module as desired. MAXPD makes use of the world-class monochromatic beam available at XPD (usually ~67 keV), with which we collect both angular dispersive X-ray diffraction data and X-radiographic imaging. The first General User experiments took place in March 2018. Final Science Commissioning beamtime took place in August of last year, and the full General User program for MAXPD began in the 2018-3 cycle. In this seminar, I will give an overview of the science drivers behind the development of the endstation, some of its unique capabilities, some representative results from recent experiments conducted over the last two cycles at MAXPD, and where we are looking to go as we look to the future.
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RIKEN Lunch Seminar
"Electric dipole moments in the era of the LHC"
Presented by Jordy de Vries, University of Massachusetts Amherst, Riken BNL
Thursday, May 9, 2019, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
The search for an understanding of fundamental particle physics that goes beyond the Standard Model (SM) has grown into a worldwide titanic effort. Low-energy precision experiments are complementary to collider searches and, in certain cases, can even probe higher energy scales directly. However, the interpretation of a potential signal, or lack thereof, is complicated because of the non-perturbative nature of low-energy QCD. I will use the search for electric dipole moments (EDMs), which aims to discover beyond-the-SM CP violation, as an example to illustrate these difficulties and how they can be overcome by combining (chiral) effective field theory and lattice QCD. I discuss how EDM experiments involving complex systems like nucleons, nuclei, atoms, and molecules constrain possible CP-violating interactions involving the Higgs boson, how these constraints match up to direct LHC searches, and the relevance of and strategies for the improvement of the hadronic and nuclear theory.
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Environmental & Climate Sciences Department Seminar
"High-throughput field phenotyping of photosynthetic capacity using hyperspectral imaging"
Presented by Katherine Meacham, Univ. of Illinois
Thursday, May 9, 2019, 11 am
Large Conference Room, Bldg. 490Hosted by: Angie Burnett
Improved photosynthetic rates have been shown to increase crop biomass, making improved photosynthesis a focus for driving future grain yield increases. Improving the photosynthetic pathway offers opportunity to meet food demand, but requires high throughput measurement techniques to detect photosynthetic variation in natural accessions and transgenically improved plants. Gas exchange measurements are the most widely used method of measuring photosynthesis in field trials but this process is laborious and slow, and requires further modeling to estimate meaningful parameters and to upscale to the plot or canopy level. In field trials of tobacco with modifications made to the photosynthetic pathway, we infer key photosynthetic parameters from imaging spectroscopy using a partial least squares regression technique. We used two hyperspectral cameras with resolution 2.1nm in the visible range and 4.9nm in the NIR. Ground-truth measurements from leaf-level photosynthetic gas exchange, full-range (400-2500nm) hyperspectral reflectance and extracted pigments support the model. The results from a range of wild-type cultivars and from genetically modified germplasm offer a high-throughput screening tool for crop trials aimed at identifying increased photosynthetic capacity.
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Physics Colloquium
"Mu*STAR Accelerator-Driven Subcritical Molten-Salt All-Purpose non-Nuclear Reactor"
Presented by Rolland Johnson, Muons Inc.
Tuesday, May 7, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: George Redlinger
The Mu*STAR BHAG[1] is: To make superconducting RF accelerators so powerful and efficient that they make enough neutrons to produce nuclear energy for electricity or for process heat at less cost than from wind, solar, or natural gas, without weapons proliferation legacies of enrichment and chemical reprocessing, by burning unwanted nuclear materials. The arguments are presented to support that such a goal is possible in the near future. [1] BHAG: Big Hairy Audacious Goal, from "Built to Last: Successful Habits of Visionary Companies" by Jim Collins and Jerry Porras (2004)
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NT/RIKEN Seminar
"Relativistic Hydrodynamic Fluctuations"
Presented by Gokce Basar, UiC
Friday, May 3, 2019, 2 pm
Small Seminar Room, Bldg. 510Hosted by: Niklas Mueller
We present a general systematic formalism for describing dynamics of fluctuations in an arbitrary relativistic hydrodynamic flow, including their feedback (known as long-time hydrodynamic tails) in a deterministic way. The fluctuations are described by two-point equal-time correlation functions. We introduce a definition of equal time in a situation where the local rest frame is determined by the local flow velocity, and a method of taking derivatives and Wigner transforms of such equal-time correlation functions, which we call confluent. The Wigner functions satisfy evolution equations that describes the relaxation of the out-of-equilibrium modes. We find that the equations for confluent Wigner functions nontrivially match with the kinetic equation for phonons propagating on an arbitrary background, including relativistic inertial and Coriolis forces due to acceleration and vorticity of the flow. We also describe the procedure of renormalization of short-distance singularities which eliminates cutoff dependence, allowing efficient numerical implementation of these equations.
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Special Particle Physics Seminar
"Observation of CP violation in charm decays"
Presented by Angelo Di Canto, BNL
Friday, May 3, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
The existence of CP violation in the decays of strange and beauty mesons is well established experimentally by numerous measurements. By contrast, CP violation in the decays of charm particles has so far escaped observation. This seminar reports on the first observation of CP violation in charm decays thought the measurement of the difference between the time-integrated CP asymmetries in D0 -> K- K+ and D0 -> pi- pi+ decays. The measurement has been performed using the full data set of proton-proton collisions collected by LHCb in 2011-2018, which corresponds to an integrated luminosity of 9fb-1. In addition, a brief overview of recent measurements of mixing and mixing-induced CP violation in charm mesons at LHCb is also presented.
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Particle Physics Seminar
"Dark Matter Searches with the ATLAS Detector at the LHC"
Presented by Arely Cortes Gonzalez, CERN
Thursday, May 2, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Michael Begel
The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC proton-proton collisions. The results of these searches on the 13 TeV data, their interpretation, and the possible evolution of the search program will be presented.
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RIKEN Lunch Seminar
"The Chiral Qubit: quantum computing with chiral anomaly"
Presented by Dmitri Kharzeev, Stony Brook University and BNL
Thursday, May 2, 2019, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
The quantum chiral anomaly enables a nearly dissipationless current in the presence of chirality imbalance and magnetic field – this is the Chiral Magnetic Effect (CME), observed recently in Dirac and Weyl semimetals. We propose to utilize the CME for the design of qubits potentially capable of operating at THz frequency, room temperature, and the coherence time to gate time ratio of about 10^4 . The proposed "Chiral Qubit" is a micron-scale ring made of a Weyl or Dirac semimetal, with the |0> and |1> quantum states corresponding to the symmetric and antisymmetric superpositions of quantum states describing chiral fermions circulating along the ring clockwise and counter-clockwise. A fractional magnetic flux through the ring induces a quantum superposition of the |0> and |1> quantum states. The entanglement of qubits can be implemented through the near-field THz frequency electromagnetic fields.
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Nuclear Physics Seminar
"Reviewing the AGS Heavy Ion Program and Looking Forward to the Fixed-Target Program at STAR"
Presented by Prof. Daniel Cebra, UC Davis
Tuesday, April 30, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
In the 1980's and 90's the AGS initiated a heavy-ion beam program with both silicon and gold beams. A suite of dedicated experiments established the systematics for production of light charged particles, strangeness, light nuclei, and anti-particles, as well as systematics for flow and femtoscopy. Those experiments established the design of the RHIC detectors and trained the personnel who would become leaders in the RHIC program. Recently, there has been renewed interest in the energy region covered by the AGS heavy-ion program. New facilities are being built Germany and Russia and proposed in Japan and China. And a conclusion of the first beam energy scan at RHIC was that it would be necessary to revisit the AGS energy range by installing a fixed-target within the STAR experiment. This talk will review key results from the AGS heavy-ion program, and those to results from the STAR fixed-target test runs, and outline the proposed physics program.
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Particle Physics Seminar
""Measure what is measurable and make measurable what is not so - Uncover new physics with bosons at the LHC and upgrades of the CMS detector to maximize the discovery potential""
Presented by Mia Liu, FNAL
Monday, April 29, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The Standard Model describes the building blocks of matter and their interactions. It has been tested extensively with experimental data and found to be incredibly successful in describing nature. Discovering the Higgs boson in 2012 at the LHC completed the picture of the SM. The LHC is at the forefront of directly searching for new physics which is Beyond-Standard-Model (BSM), and I will discuss searches for supersymmetric partners of the electroweak bosons, as well as measurement of an extremely rare process with three WWW bosons as stringent tests of the SM. I will also discuss the instrumentation which enables such studies. The discussion includes the recently completed CMS Phase-1 pixel upgrade, as well as the R&D studies towards solving the future trigger and computing challenges using innovative machine learning approaches in future high energy experiments.
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Particle Physics Seminar
"Searching for Higgs Pair Production at the LHC"
Presented by Elizabeth Brost, Northern Illinois University
Thursday, April 25, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
Since the discovery of the Higgs boson in 2012, the particle physics community at the Large Hadron Collider (LHC) has been hard at work studying its properties, and comparing them to the predictions of the Standard Model (SM), including the couplings of the Higgs boson to itself and to other particles. The Higgs self-coupling can be measured directly in the Higgs pair production process, and will provide insight into the nature of electroweak symmetry breaking. In the SM, the di-Higgs cross section in proton-proton collisions is very small. However, a wide range of beyond-the-SM models predict enhancements to the di-Higgs production rate, which motivates searching for di-Higgs production even now, when the SM cross section is too small to measure in the current LHC dataset. Looking forward, the LHC Run 3 and HL-LHC will bring a new set of challenges, including more proton-proton collisions per bunch crossing. Extracting rare physics signatures from this busier environment will be difficult for the current ATLAS trigger system. In this talk, I will present current and future ATLAS searches for hh production using a variety of final states, and discuss the use of future track triggers in upgrades to the ATLAS trigger system.
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NT/RIKEN Seminar
"Parton distributions in Euclidean space"
Presented by Anatoly Radyushkin, ODU/JLab
Friday, April 19, 2019, 2 pm
Building 510, CFNS Room 2-38Hosted by: Niklas Mueller
To extract parton distributions from the lattice simulations, one needs to consider matrix elements M(z,p) of bilocal correlators of parton fields [generically written as φ(0)φ(z)] at spacelike separations z=(0,0,0,z_3). A transition to PDFs may be proceeded by taking a Fourier transform either with respect to z_3 for fixed p_3 (which gives X. Ji's quasi-PDFs), or with respect to the Lorentz-invariant variable ν=-(zp) for fixed values of another Lorentz invariant z^2 [which results in pseudo-PDFs].These functions are interesting on their own, and I will discuss, in the continuum case, their general properties, the connection between the two types of functions, and their relation with the usual light-cone PDFs. I will outline the algorithm of extracting the PDFs through the use of the so-called "reduced Ioffe-time distributions",and illustrate this pseudo-PDF-oriented approach on the example of exploratory lattice simulations performed by Orginos et al.
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Particle Physics Seminar
"Dissecting the Higgs boson with ATLAS and leptons"
Presented by Quentin Buat, CERN
Thursday, April 18, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
Using data taken during the first years of the LHC Run2, ATLAS has firmly established the coupling of the Higgs boson to the tau lepton, thus directly confirming the existence of leptonic Yukawa interactions. In this talk, I will present the cross-section measurements performed by ATLAS in the di-tau final state with a partial Run2 dataset and discuss the prospects of the analysis with the full Run2 dataset and beyond. I will also discuss the status of the search for the muonic Yukawa interaction.
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Condensed-Matter Physics & Materials Science Seminar
""Superconductivity and magnetism at ferroelectric critical point""
Presented by Alexander Balatsky, UConn Nordita
Thursday, April 18, 2019, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Ilya Drozdov
It is well established that multiple entangled orders emerge in quantum materials at criticality: eg superconducting states develop in the vicinity of magnetic phases. I will make the case that similar phenomena occur in quantum paraelectrics. Recent observations of strain and O18 isotope substitution in doped STO support the view of the key role critical ferroelectric fluctuations play in producing superconductivity. Looking beyond superconductivity, I will illustrate how quantum ferroelectric fluctuations can induce magnetic fluctuations due to recently proposed phenomenon of dynamic multiferroicity.
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Environmental & Climate Sciences Department Seminar
"Using High-Resolution Observations to Improve a Low-Resolution Global Climate Model"
Presented by Greg Elsaesser, NASA GISS
Thursday, April 18, 2019, 11 am
Large Conference Room, Bldg. 490Hosted by: Mike Jensen
This talk will begin with an overview of recent development in the representation of deep convection in the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). Global satellite remote sensing products are important references for continual GCM development and evaluation, but such products often provide data at coarse temporal and/or spatial resolutions, thus making it difficult to conceptualize and evaluate "process representations" in a GCM. I will discuss the various approaches I am taking to average global satellite retrievals in new ways, coincident with efforts to use new DOE/ARM observations, to derive composite high-resolution evolutions of deep convection and the nearby environment. These depictions will not only inform future development, but they are also crucial for ensuring that recent improved mean-state representations are not the result of errors cancelling at the process level.
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Nuclear Physics Seminar
"Recent Results from COMPASS"
Presented by Ana-Sofia Nunes, BNL
Tuesday, April 16, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Oleg Eyser
COMPASS is a fixed target experiment at the CERN SPS that has been collecting data since 2002 and was already approved to run in 2021. It uses unique beams of naturally polarized muons and unpolarized hadrons of 160, 190 or 200 GeV impinging on polarized and unpolarized proton, isoscalar or heavy targets to study fundamental aspects of QCD, as the structure of nucleons, hadron spectroscopy and the pion polarizability. The collected data allow measurements on the spin structure of nucleons, not only in the collinear approximation but also on nucleon tomography, either via deeply virtual Compton scattering (DVCS) and deeply virtual meson production (DVMP) which give access to generalized parton distributions (GPDs), or via semi-inclusive deep inelastic scattering (SIDIS) and polarized Drell-Yan (DY) which give access to transverse-momentum dependent parton distribution functions (TMDs). Moreover, hadron multiplicities extracted from semi-inclusive deep inelastic scattering data can be used as input for the computation of fragmentation functions (FFs) in QCD fits. A selection of the latest published and preliminary results of COMPASS in the scope of the study of the structure of nucleons and the hadronization of quarks will be presented.
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Condensed Matter Physics and Materials Science - The Myron Strongin Seminar
"Disappearance of Superconductivity Due to Vanishing Coupling in the Overdoped High-Temperature Cuprate Superconductors"
Presented by Tonica Valla, BNL
Monday, April 15, 2019, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Weiguo Yin and Jing Tao
In high-temperature cuprate superconductors, superconductivity is accompanied by a "plethora of orders", and phenomena that may compete, or cooperate with superconductivity, but which certainly complicate our understanding of origins of superconductivity in these materials. While prominent in the underdoped regime, these orders are known to significantly weaken or completely vanish with overdoping. Here, we approach the superconducting phase from the more conventional highly overdoped side. We present angle-resolved photoemission spectroscopy (ARPES) studies of Bi2Sr2CaCu2O8+d (Bi2212) single crystals cleaved and annealed in ozone to increase the doping all the way to the metallic, non-superconducting phase. We show that the mass renormalization in the antinodal region of the Fermi surface, associated with the structure in the quasiparticle self-energy, that possibly reflects the pairing interaction, monotonically weakens with increasing doping and completely disappears precisely where superconductivity disappears. This is the direct evidence that in the overdoped regime, superconductivity is determined by the coupling strength. A strong doping dependence and an abrupt disappearance above the transition temperature (Tc) eliminate the conventional phononic mechanism of the observed mass renormalization and identify the onset of spin-fluctuations as its likely origin.
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Physics Colloquium
"Future Circular Collider"
Presented by Michael Benedikt, CERN
Friday, April 12, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: George Redlinger & Maria Chamizo Llatas
The global Future Circular Collider Study, launched in 2014 by CERN as host institute, has published its conceptual design report by the end of 2018, as input to the update of the European Strategy for Particle Physics. Today, a staged Future Circular Collider (FCC), consisting of a luminosity-frontier highest-energy electron-positron collider (FCC-ee) followed by an energy-frontier hadron collider (FCC-hh), promises the most far-reaching physics program for the post-LHC era. FCC-ee is a precision instrument to study the Z, W, Higgs and top particles, and o?ers unprecedented sensitivity to signs of new physics. Most of the FCC-ee infrastructure can later be reused for the subsequent hadron collider, FCC-hh. The FCC-hh provides proton-proton collisions at a centre-of-mass energy of 100 TeV and can directly produce new particles with masses of up to several tens of TeV. This collider will also measure the Higgs self-coupling and explore the dynamics of electroweak symmetry breaking. Heavy-ion collisions and ep collisions (FCC-eh) further contribute to the breadth of the overall FCC program. The integrated FCC infrastructure will serve the particle physics community through the end of the 21st century. This presentation will summarize the conceptual designs of FCC-ee and FCC-hh, covering the machine concepts, the R&D for key technologies, infrastructure planning, initial considerations for the experiments, and a possible implementation schedule.
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NT / RIKEN Seminar
"A Complex Path Around the Sign Problem"
Presented by Paolo Bedaque, U Maryland
Friday, April 12, 2019, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Niklas Mueller
The famous "sign problem" is the main roadblock in the path to a Monte Carlo solution of QCD at finite densities and the study of real time dynamics. We review a recent developed approach to this problem based on deforming the domain of integration of the oath integral into complex field space. After discussing the math involved in the complex analysis of multidimensional spaces we will talk about the advantages/disadvantages of using Lefschetz thimbles, "learnifolds" and "optimized manifolds" as the alternative integration manifold as well as the algorithms that go with them. Several examples of lower dimensional field theories will be presented.
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Particle Physics Seminar
"Neutrino Interaction Modeling and Tuning"
Presented by Libo Jiang, University of Pittsburgh
Thursday, April 11, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Mary Bishai
GENIE is a well-knows event generator provides the simulation of neutrino interactions, and performs a highly-developed global analysis of neutrino scattering. It handles all neutrinos and targets, and all processes relevant from MeV to PeV energy scales. I am going to present the modelling of neutrino interactions and results of tuning against experimental data.
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Condensed-Matter Physics & Materials Science Seminar
"Tailoring electronic and thermal properties of bulk Cu26T2(Ge,Sn)6S32 colusite through defects engineering and functionalization of the conductive network"
Presented by Emmanuel Guilmeau, CRISMAT Laboratory, Caen, France
Thursday, April 11, 2019, 1:30 pm
Bldg. 734, ISB Conference Room 201 (upstairs)Hosted by: Qiang Li
A complete study of the structure and thermoelectric properties of colusite Cu26T2(Ge,Sn)6S32 (T = V, Cr, Mo, W) is presented. A brief introduction provides a state-of-theart/survey of thermoelectric sulfides, with a special focus on the structural features and transport properties relationship in Cu-based sulfides. In the first part of this presentation, we highlight the key role of the densification process on the formation of short-to-medium range structural defects in Cu26V2Sn6S32 [1]. A simple and powerful way to adjust carrier concentration combined with enhanced phonon scattering through point defects and disordered regions is described. By combining experiments with band structure and phonons calculations, we elucidate, for the first time, the underlying mechanisms at the origin of the intrinsically low thermal conductivity in colusite samples as well as the effect of S vacancies and antisite defects on the carrier concentration. In the second part, we demonstrate the spectacular role of the substitution of V5+ by hexavalent T6+ cations (Cr, Mo and W) on the electronic properties, leading to high power factors [2]. In particular, Cu26Cr2Ge6S32 shows a value of 1.53 mW m-1 K-2 at RT that reaches a maximum value of 1.94 mW m-1 K-2 at 700 K. The rationale is based on the concept of conductive "Cu-S" network, which in colusites corresponds to the more symmetric parent sphalerite structure. The interactions within the mixed octahedral-tetrahedral [TS4]Cu6 complexes are shown to be responsible for the outstanding electronic transport properties. [1] C. Bourgès et al., J. Amer. Chem. Soc. 140 (2018) 2186 [2] V. Pavan Kumar et al., Adv. Energy Mater. 9 (2019) 1803249
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Environmental & Climate Sciences Department Seminar
"Simulating Mixed-Phase Clouds at High Latitudes: Model Evaluation, Improvement, and Interactions with Aerosol"
Presented by Xiahong Liu, Univ. Wyoming
Thursday, April 11, 2019, 11 am
Large Conference Room, Bldg. 490Hosted by: Damao Zhang
Mixed-phase clouds are frequently observed in the Arctic and Antarctic and over the Southern Ocean, and have important impacts on the surface energy budget and regional climate. Global climate models (GCMs), an important tool for studying the climate change still have large biases in simulating the mixed-phase cloud properties, including supercooled liquid amount and liquid and ice phase partitioning. In this talk, I will present our recent works on mixed-phase clouds: (1) improving the representations of subgrid mixing and partitioning between cloud liquid and ice in mixed-phase clouds in the DOE's Energy Exascale Earth System Model (E3SM). Model simulations are evaluated against observation data obtained in the DOE Atmospheric Radiation Measurement (ARM) Program's field campaigns and long-term ground-based multi-sensor measurements; and (2) investigating the effects of aerosols, including dust and sea spray aerosol, on mixed-phase clouds. We found that dust, as ice nucleating particles (INPs), induces a global net warming via its indirect effect on mixed-phase clouds with a predominant warming in the NH midlatitudes and a cooling in the Arctic. INP sources of sea spray aerosol vary with time and geographic location with the maximum contribution in the marine boundary layer over the Southern Ocean, where dust has a limited influence. Modeled INP concentrations are compared with observations from different campaigns (e.g., MARCUS, SOCRATES, CAPRICORN).
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Condensed-Matter Physics & Materials Science Seminar
"Importance of electron interactions in understanding the photo-electron spectroscopy and the Weyl character of MoTe2"
Presented by Niraj Aryal, Florida State University
Thursday, April 11, 2019, 11 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Weiguo Yin
Weyl semimetals are crystalline materials that host pairs of chiral Weyl Fermions (WFs) as low energy excitations. Such WFs act as sources and sinks of Berry curvature and can contribute to many exotic transport properties. Recently, inversion symmetry broken transition metal dichalcogenide materials like MoTe2 and WTe2 have been predicted to host type-II WFs by DFT calculations and ARPES experiments. However, quantum oscillation experiments (QOE) disagree with the DFT calculations thus raising doubt about the existence of Weyl physics in these materials [1]. In order to address this discrepancy, we studied the role of electron interactions in Td-MoTe2 by employing DFT where the onsite Coulomb repulsion (Hubbard U) for the Mo 4d states is included within the DFT+U scheme. We found that in addition to explaining the QOE, inclusion of electron interaction is needed to explain the light-polarization dependence measured by ARPES [2]. We also found that while the number of Weyl points (WPs) and their position in the Brillouin Zone change as a function of U, a pair of such WPs very close to the Fermi level survive the inclusion of these important corrections. Our calculations suggest that the Fermi surface of Td-MoTe2 is in the vicinity of a correlations-induced Lifshitz transition which can be probed experimentally. If time allows, I will also present briefly our study of the interface between topological insulator and non-topological materials which are important for band engineering and studying emergent fundamental phenomena. References [1] D. Rhodes, R. Schonemann, N. Aryal, Q.R. Zhou et al., Bulk Fermi surface of the Weyl type-II semimetallic candidate ?-MoTe2, Phys. Rev. B 96, 165134 (2017). [2] N. Aryal and E. Manousakis, Importance of electron correlations in understanding the photo-electron spectroscopy and the Weyl character of MoTe2, Phys. Rev. B 99, 035123 (2019).
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Particle Physics Seminar
"The Search for the dark vector boson"
Presented by Diallo Boye, BNL
Wednesday, April 10, 2019, 4 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricolli
Hidden sector or dark sector states appear in many extensions to the Standard Model, to provide a particle candidate for dark matter in universe or to explain astrophysical observations such the as positron excess observed in the cosmic radiation flux. A hidden or dark sector can be introduced with an additional U(1)d dark gauge symmetry. The discovery of the Higgs boson during Run 1 of the Large Hadron Collider opens a new and rich experimental program based on the Higgs Portal. This discovery route uses couplings to the dark sector at the Higgs level, which were not experimentally accessible before. These searches use the possible exotic decays: H -> Z Zd -> 4l and H -> Zd Zd -> 4l. Here Zd is a dark vector boson. We have experience of this search from the Run 1 period of the LHC using the ATLAS detector at CERN. These results showed (tantalizingly) two signal events where none were expected, so that in the strict criteria of High Energy Physics, the result was not yet statistically significant. The Run 1 analysis for 8 TeV collision energy is further developed in Run 2 with 13 TeV collision energy, to expand the search area, take advantage of higher statistics, a higher Higgs production cross section, and substantially better performance of the ATLAS detector. The analysis is extended to search for heavier scalars decaying to dark vector bosons.
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CFN Special Colloquium
"Discovering novel materials, and novel physics, with first-principles"
Presented by Nicola Marzari, École Polytechnique Fédérale de Lausanne (EPFL)
Wednesday, April 10, 2019, 3:30 pm
CFN, Bldg 735, 2nd Floor Seminar RoomHosted by: Mark Hybertsen
First-principles simulations are one of the greatest accelerators in the world of science and technology. To provide some context, one could mention that 30,000 papers on density-functional theory are published every year; that 12 of these are in the top-100 most-cited papers in the entire history of science, engineering, and medicine; or that the doubling in capacity every 14 months has been the underwriter of computational science for the past 30 years. I'll highlight some of my own scientific, structural, and policy perspectives on this, taking as a case study the discovery of novel two-dimensional materials and of their properties and applications. I'll then argue how the need to calculate materials properties often forces a critical evaluation of some stalwarts of condensed-matter physics: in this case, learning that phonons are just a high-temperature approximation for heat carriers, or discovering that the Boltzmann transport equation can be generalized to describe simultaneously the propagation and interference of phonon wavepackets, thus unifying the description of thermal transport in crystals and glasses. Bio: Nicola Marzari holds the chair of Theory and Simulation of Materials at the École Polytechnique Fédérale de Lausanne, where he is also the director of the Swiss National Centre for Competence in Research MARVEL, on Computational Design and Discovery of Novel Materials (2014-26). Previous tenured appointment include the Toyota Chair for Materials Engineering at the Massachusetts Institute of Technology and the first Statutory (University) Chair of Materials Modelling at the University of Oxford, where he was also the director of the Materials Modelling Laboratory. He is the current chairman of the Psi-k Charity and Board of Trustees, and holder of an Excellence Chair at the University of Bremen.
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BWIS Sponsored Event
"How Beauty Leads Physics Astray"
Presented by Sabine Hossenfelder, Frankfurt Institute for Advanced Studies, Germany
Tuesday, April 9, 2019, 5 pm
Large Seminar Room, Bldg. 510Hosted by: Vivian Stojanoff
To develop fundamentally new laws of nature, theoretical physicists often rely on arguments from beauty. Simplicity and naturalness in particular have been strongly influential guides in the foundations of physics ever since the development of the standard model of particle physics. In this lecture I argue that arguments from beauty have led the field into a dead end and discuss what can be done about it.
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Physics Colloquium
"Do Women Get Fewer Citations Than Men?"
Presented by Sabine Hossenfelder, Frankfurt Institute for Advanced Studies, Germany
Tuesday, April 9, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Berndt Mueller
I will talk about the results of a citation analysis on publication data from the arXiv and inspire in which we explored gender differences. I will further explain how we can use bibliometric analysis to improve the efficiency of knowledge discovery.
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Condensed-Matter Physics & Materials Science Seminar
""Charge and lattice entanglement in quantum materials observed by TEM: Tb2Cu0.83Pd0.17O4 and Cu2S""
Presented by Wei Wang, Institute of Physics, Chinese Academy of Sciences, Beijing
Tuesday, April 9, 2019, 3 pm
Bldg. 480, Conference RoomHosted by: Jing Tao
Plenty of physical properties in strongly electron correlated system are thought to arise from intricate interplay among charge, spin, orbital and lattice. Understanding the structural origin of these functionalities, such as superconductivity, multiferroics, etc, has attracted tremendous attention for decades. Using electron diffraction technique in TEM, we recently studied the modulated structure in Tb2Cu0.83Pd0.17O4 compound and phase transition in Cu2S. After a brief introduction of TEM techniques that I have employed for the study, I will report observations of electron-beam-induced smectic-nematic phase transitions in Tb2Cu0.83Pd0.17O4. Electron diffraction and HAADF-STEM images indicate a superlattice structure with Cu/Pd displacements perpendicular to the Cu-O plane on Cu sites. In addition, the superlattice modulation undergoes a reversible smectic-nematic phase transition under the electron beam illumination. Our in situ TEM results imply that the modulated structure root in a charge ordering at Cu sites. Then I will switch to an on-going study of the Cu2S at high temperature. Previous reports show that the crystal structural of Cu2S can be manipulated by electron beam illumination, suggesting a strong coupling between charge and lattice. To explore the structural phase transition and to have a better understanding of superionic behavior in this material, we focus on diffuse scattering in the electron diffraction patterns obtained at high temperatures, which results from short range ordering of Cu atoms. Electron diffraction tomographyic data were collected in order to reconstruct the real-space structure for Cu atoms. Preliminary results will be shown followed by a discussion with early-stage interpretations.
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High Energy Theory Seminar
"Dark Matter — or What?"
Presented by Sabine Hossenfelder, Frankfurt Institute for Advanced Studies, Germany
Tuesday, April 9, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Berndt Mueller
In this talk I will explain (a) what observations speak for the hypothesis of dark matter, (b) what observations speak for the hypothesis of modified gravity, and (c) why it is a mistake to insist that either hypothesis on its own must explain all the available data. The right explanation, I will argue, is instead a suitable combination of dark matter and modified gravity, which can be realized by the idea that dark matter has a super fluid phase.
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NT / RIKEN seminar
"The Color Glass Condensate density matrix: Lindblad evolution, entanglement entropy and Wigner functional"
Presented by Alex Kovner, U Connecticut
Friday, April 5, 2019, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Niklas Mueller
We introduce the notion of the Color Glass Condensate (CGC) density matrix ρ̂ . This generalizes the concept of probability density for the distribution of the color charges in the hadronic wave function and is consistent with understanding the CGC as an effective theory after integration of part of the hadronic degrees of freedom. We derive the evolution equations for the density matrix and show that it has the celebrated Kossakowsky-Lindblad form describing the non-unitary evolution of the density matrix of an open system. Additionally, we consider the dilute limit and demonstrate that, at large rapidity, the entanglement entropy of the density matrix grows linearly with rapidity according to dSe/dy=γ, where γ is the leading BFKL eigenvalue. We also discuss the evolution of ρ̂ in the saturated regime and relate it to the Levin-Tuchin law and find that the entropy again grows linearly with rapidity, but at a slower rate. Finally we introduce the Wigner functional derived from this density matrix and discuss how it can be used to determine the distribution of color currents, which may be instrumental in understanding dynamical features of QCD at high energy.
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Physics Colloquium
"Views and news on chiral transport"
Presented by Karl Landsteiner
Thursday, April 4, 2019, 4 pm
Large Seminar Room, Bldg. 510Hosted by: Niklas Mueller
I present an effective action approach to chiral transport. Chiral Magnetic and Chiral Vortical Effect are treated in exact parallel and result in the known dependence on chemical potential and temperature. The approach sheds light on some of the more obscure features of chiral transport such as covariant and consistent anomalies and a seeming mismatch of the derivative expansion. As a related application I will comment on the thermal Hall effect on 2D topological insulators. Then I discuss a new example of chiral transport: anomalous Hall viscosity at the quantum critical point of the Weyl-semimetal/insulator transition. Results from a holographic model will be compared to a weak coupling quantum field theory analysis.
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Particle Physics Seminar
"Flavour physics with dynamical chiral fermions"
Presented by Peter Boyle, University of Edinburgh
Thursday, April 4, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Hooman Davoudiasl
I discuss recent simulations with dynamical chiral fermions. In particular I focus on neutral kaon mixing amplitudes in and beyond the standard model, calculated for the first time with physical quark masses. A puzzle in the non-perturbative renormalisation of the BSM operators is resolved. The prospects for extension of this calculation to B-meson mixing amplitudes is discussed, and initial results for the standard model B mixing amplitudes presented. Prospects for future calculations over the next five years are considered.
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Physics Colloquium
"Prospects on nucleon tomography"
Presented by Herve Moutard, Université Paris-Saclay
Wednesday, April 3, 2019, 3 pm
Large Seminar Room, Bldg. 510Hosted by: Salvatore Fazio
Much attention has been devoted in recent years to the three-dimensional quark and gluon structure of the nucleon. In particular the concept of Generalized Parton Distributions promises an understanding of the generation of the charge, spin, and energy-momentum structure of the nucleon by its fundamental constituents. Forthcoming measurements with unprecedented accuracy at Jefferson Lab and at a future electron-ion collider will presumably challenge our quantitative description of the three-dimensional structure of hadrons. To fully exploit these future experimental data, new tools and models are currently being developed. After a brief reminder of what make Generalized Parton Distributions a unique tool to understand the nucleon structure, we will discuss the constraints provided by the existing measurements and review recent theoretical developments. We will explain why these developments naturally fit in a versatile software framework, named PARTONS, dedicated to the phenomenology and theory of GPDs.
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HET Seminar
"Lattice QCD Inputs For Neutrino-Nucleon Scattering"
Presented by Raza Sufian, Jefferson Lab
Wednesday, April 3, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Aaron Meyer
We present lattice QCD calculation of nucleon axial and electromagnetic (up, down, strange and charm) form factors and discuss their impact on the understanding of neutrino-nucleon scattering. In a phenomenological study, using a combination of lattice QCD calculation of the strange-quark form factors, and MiniBooNE experimental neutrino scattering differential cross-section data in a limited kinematic regime, we obtain a precise determination of the weak axial form factor and of the corresponding neutral current weak-axial charge. We further show how a direct lattice QCD determination of neutral current weak-axial charge enable us to predict the BNL E734 data for the neutrino neutral current scattering differential cross section to high precision. We discuss how a direct lattice QCD calculation of neutrino-nucleon scattering cross sections can help to isolate nuclear effects in the neutrino-nucleus scattering.
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Condensed-Matter Physics & Materials Science Seminar
"Topological semimetals predicted from first-principles and theoretical approaches"
Presented by Jiawei Ruan, School of Physics, Nanjing University, China
Monday, April 1, 2019, 11 am
Building 734, Seminar Room 201Hosted by: Weiguo Yin
Weyl semimetals are new states of matter which feature novel Fermi arcs and exotic transport phenomena. Based on first-principles calculations, we report that the HgTe-class materials [1] as well as four chalcopyrites [2] are ideal Weyl semimetals, having largely separated Weyl points and uncovered Fermi arcs that are amenable to experimental detections. We also construct a minimal effective model to capture the low-energy physics of this class of Weyl semimetals. Our discovery is a major step toward a perfect playground of intriguing Weyl semimetals and potential applications for low-power and high-speed electronics. Besides the ideal Weyl semimetals, I will talk about Non-Hermitian nodal-line semimetals with an anomalous bulk-boundary correspondence [3]. I will also present recent results of saddle surface in topological materials and a new method to construct a simplified tight-binding model based on group theory analysis. [1] JR et al., Nature communications 7, 11136 (2016). [2] JR et al., PRL 116, 226801 (2016). [3] H. Wang, JR, and H. Zhang, PRB 99, 075130 (2019).
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NT/RIKEN Seminar
"Toward a unified description of both low and high ptparticle production in high energy collisions"
Presented by Jamal Jalilian-Marian, Baruch College, City University of New York
Friday, March 29, 2019, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Niklas Mueller
Inclusive particle production at high p_t is successfully described by perturbative QCD using collinear factorization formalism with DGLAP evolution of the parton distribution functions. This formalism breaks down at small Bjorken x (high energy) due to high gluon density (gluon saturation) effects. The Color Glass Condensate (CGC) formalism is an effective action approach to particle production at small Bjorken x (low p_t) which includes gluon saturation. The CGC formalism nevertheless breaks down at intermediate/large Bjorken x, corresponding to the high p_t kinematic region in high energy collisions. Here we describe the first steps taken towards the derivation of a new formalism, with the ultimate goal of having a unified formalism for particle production at both low and high p_t in high energy hadronic/heavy ion collisions.
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HET Lunch Discussion
"Discussion on arXiv 1307.5458: Implication of neutrino backgrounds on the reach of next generation dark matter direct detection experiments"
Presented by Dr Gopolang Mohlabeng, Brookhaven National Laboratory
Friday, March 29, 2019, 12:15 pm
Building 510, Room 2-160Hosted by: Peter Denton
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Physics Colloquium
"Quantum Information Science Landscape, Vision, and NIST"
Presented by Carl Williams, NIST
Tuesday, March 26, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Andrei Nomerotski
The first part of the colloquium will provide an overview of United States government's interest in quantum information science from the National Strategic Overview for Quantum Information Science that established the policy objectives for this administration to the National Quantum Initiative Act that formalizes parts of this strategy for key civilian science agencies. This portion of the talk will conclude with placing the United States strategy in the global context and describe how the United States plans to establish the foundation for the quantum 2.0 economy. The second part of the colloquium will begin with a high-level overview of NIST, of NIST's interest in Quantum Information Science, before talking briefly about some interesting highlights from NIST laboratories. Moving from the highlights, the talk will explore ongoing and future metrological applications followed by some hypothetical conjectures of future technological applications with a focus on how quantum information science and its technology may impact fundamental physics from exploring potential time variation of fundamental constants to future probes of dark matter and gravitational waves.
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Particle Physics Seminar
"Deep learning at the edge of discovery at the LHC"
Presented by Javier Duarte, FNAL
Monday, March 25, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The discovery of the Higgs boson at the Large Hadron Collider in 2012 opened a new sector for exploration in the standard model of particle physics. Recent developments, including the use of deep learning to identify a complex but common decay of the Higgs boson to bottom quarks, have expanded our ability to study the production of Higgs bosons with very large momenta. By studying these Higgs bosons and measuring their momentum spectrum, we may be able to discover new physics at very high energy scales inaccessible directly at the LHC. I will explain these searches and the direction that deep learning is taking in particle physics, especially how it's changing the way we think about the trigger, event reconstruction, and our computing paradigm.
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Particle Physics Seminar
"Installation and preliminary results from ProtoDUNE Single Phase experiment at CERN"
Presented by Maura Spanu, BNL
Thursday, March 21, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
DUNE is a leading-edge, international experiment for neutrino science and proton decay. Its ambitious physics program requires a careful prototyping of the engineering solutions envisaged for the scale-up of the LArTPC technology, as well as a careful control of the systematics through the acquisition of a deep knowledge of the detector response and performances. ProtoDUNE is an extensive prototype program (ProtoDUNE) development at the European Research Center (CERN) Neutrino Platform facility with the aim to answer to all the open questions about DUNE design. The Single Phase prototype (ProtoDUNE SP) has been assembled in the EHN1 extension at CERN between 2016 and 2018 and it successfully took its first beam data from a dedicated SPS tertiary line from September to November 2018.
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Physics Colloquium
"Development of LArTPC for Neutrino Physics"
Presented by Xin Qian, BNL
Tuesday, March 19, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Andrei Nomerotski
Liquid Argon Time Projection Chamber (LArTPC), with its mm-scale position resolution and the full-active-volume imaging-aided calorimetry, is an excellent device to detect accelerator neutrinos at GeV energy range. This technology may hold the key to search for new CP violation in the lepton sector, to determine the neutrino mass hierarchy, to search for baryon number violation, and to search for sterile neutrino(s). In this talk, I will review the existing achievements and current status of the detector development.
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Nuclear Physics Seminar
"Modified Structure of Protons and Neutrons in Correlated Pairs"
Presented by Dr. Barak Schmookler, Center for Frontiers in Nuclear Science, Stony Brook University
Tuesday, March 19, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
It has been known for several decades that the inelastic structure of the nucleon is modified by the presence of the nuclear medium. This modification is called the EMC effect. However, there is still no consensus as to the underlying QCD-based quark-gluon dynamics driving the effect. One approach to describe the EMC effect is to slightly modify the structure of all the nucleons in the nucleus. Recent evidence, however, suggests that the EMC effect may arise due to two-nucleon Short Range Correlations (SRC), which are pairs of nucleons close together in the nucleus. If this is true, it implies that nucleons are largely unmodified most of the time, but have their structure significantly modified when they temporarily fluctuate into SRC pairs. In this presentation, I will discuss the experimental evidence linking the EMC effect to two-nucleon SRCs. I will then describe a new data-driven phenomenological model of the EMC effect based on neutron-proton SRC pairs, and I will show that this model can consistently describe the effect across nuclei.
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NT/RIKEN Seminar
"Baryons as Quantum Hall Droplets"
Presented by Zohar Komargodski, Simons Center, Stony Brook
Friday, March 15, 2019, 2 pm
Building 510, CFNS Room 2-38Hosted by: Niklas Mueller
We revisit the problem of baryons in the large N limit of Quantum Chromodynamics. A special case in which the theory of Skyrmions is inapplicable is one-flavor QCD, where there are no light pions to construct the baryon from. More generally, the description of baryons made out of predominantly one flavor within the Skyrmion model is unsatisfactory. We propose a model for such baryons, where the baryons are interpreted as quantum Hall droplets. An important element in our construction is an extended, 2+1 dimensional, meta-stable configuration of the η′ particle. Baryon number is identified with a magnetic symmetry on the 2+1 dimensional sheet. If the sheet has a boundary, there are finite energy chiral excitations which carry baryon number. These chiral excitations are analogous to the electron in the fractional quantum Hall effect. Studying the chiral vertex operators we are able to determine the spin, isospin, and certain excitations of the droplet. In addition, balancing the tension of the droplet against the energy stored at the boundary we estimate the size and mass of the baryons. The mass, size, spin, isospin, and excitations that we find agree with phenomenological expectations.
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Condensed-Matter Physics & Materials Science Seminar
"Neutron scattering study of strongly correlated systems"
Presented by Yao Shen, Fudan University, China
Monday, March 11, 2019, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Mark Dean
In strongly correlated systems, interactions between various microscopic degrees of freedom with similar energy scales can induce strong competition and frustration, leading to exotic phenomena. Here we use neutron scattering technique to study several strongly correlated systems to show how the competition and interplay between these degrees of freedom can induce different phases and properties. 1) In the pressure-induced superconductor CrAs, the competition between various magnetic interactions lead to a noncollinear helimagnetic order. In addition, CrAs exhibits a spin reorientation at a critical pressure (Pc ~ 0.6 GPa), which is accompanied by a lattice anomaly and coincides with the emergence of bulk superconductivity, indicating the strong interplay between magnetic, structural and electronic degrees of freedom. 2) FeSe, the structurally simplest iron-based superconductor, shows nematic order at 90 K, but no magnetic order in the parent phase. Our neutron scattering experiments reveal both stripe and Neel spin fluctuations that are coupled to the nematicity. The competition between these two phases suppress the magnetic order and drive the system into a nematic quantum disordered paramagnet. Similar phenomenon is observed in YFe2Ge2, in which the magnetic order is suppressed by the competition between stripe type AFM phase and in-plane FM phase. 3) In the heavily electron-doped FeSe based superconductor Li0.8Fe0.2ODFeSe (Tc=41 K), a twisted dispersion of spin excitations is observed which may be caused by the competition between itinerant and local electrons, analogous to the hole-doped cuprates which host remarkably high Tc as well. 4) In the two-dimensional triangular lattice antiferromagnet YbMgGaO4, due to the strong spin-orbit coupling and crystalline electric field (CEF), the low-lying crystal field ground state is a Kramers doublet. The geometric frustration is enhanced by the anisotropic interactions and a quantum sp
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Particle Physics Seminar
"The PROSPECT Antineutrino Detector and Early Physics Results"
Presented by Xianyi Zhang, Illinois Institute of Technology
Thursday, March 7, 2019, 1:30 pm
Small Seminar Room, Bldg. 510Hosted by: Elizabeth Worcester
PROSPECT, Precision Reactor Oscillation and SPECTrum, is a short baseline reactor antineutrino experiment. The PROSPECT antineutrino detector is an optically segmented liquid scintillator detector deployed ~7 m from a highly enriched U-235 reactor. This detector was designed to investigate discrepancies in the reactor antineutrino flux and spectrum by model-independently probing the eV-scale sterile neutrino oscillation from nuclear fission reactor, as well as precisely measuring the U-235 antineutrino spectrum. The particle multi-segment scattering in PROSPECT detector brought a typical challenge in characterizing the scintillator nonlinearity. This talk details the energy scale study for PROSPECT with data-MC comparison of detector calibrations. The detector construction, commissioning, and its early physics measurements are also presented.
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Particle Physics Seminar
"Neutrino cross sections"
Presented by Callum Wilkinson, University of Bern
Tuesday, March 5, 2019, 2 pm
Small Seminar Room, Bldg. 510Hosted by: Elizabeth Worcester
Current and planned neutrino oscillation experiments operate in the 0.1-10 GeV energy regime and use a variety of nuclear targets. At these energies, the neutrino cross section is not well understood: a variety of interaction processes are possible and nuclear effects play a significant role. This talk will give an overview of the state of neutrino cross sections, and explore their relationship with neutrino oscillation experiments.
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Particle Physics Seminar
"Measurement of LAr purity using Cosmic Muons"
Presented by Monica Nunes, IFGW/UNICAMP, Brazil
Monday, March 4, 2019, 3 pm
3-209B, Bldg. 510Hosted by: Mary Bishai
LArIAT is an experiment based on a LArTPC aiming to study relevant cross sections of charged particles with argon as well as the development of the related instrumentation. Charged particle crossing the detector excite and ionize the argon atoms and the electrons generated by the ionization are drifted in an electric field towards the anodic wire planes of the TPC. With electronegative impurities in the liquid argon, the amount of charge collected by the wires is going to be smaller and affect the quality of the results obtained in the experiment. Cosmic muons that cross the TPC between beam spills is a valuable tool for measuring the liquid argon purity inside the detector. With the electron lifetime obtained with the purity analysis based on cosmics, is possible to correct data used for all other studies based on charge collection of the LArTPC. In this seminar, I'll present the method and the results obtained in the LArIAT experiment. I'll also present other tasks that I performed on LArIAT during my PhD research.
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Particle Physics Seminar
"Status and physics potential of the JUNO experiment"
Presented by Zeyuan Yu, Institute of High Energy Physics, China
Thursday, February 28, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton multi-purpose liquid scintillator detector with an unprecedented energy resolution of 3% at 1 MeV being built in a dedicated underground laboratory in China and expected to start data taking in 2021. The main physics goal of the experiment is the determination of the neutrino mass ordering with a significance of 3-4 sigma within six years of running using electron anti-neutrinos coming from two nuclear power plants at a baseline of about 53 km. Beyond this fundamental question, JUNO will also have a very rich physics program including the precise measurement at a sub-percent level of the solar neutrino oscillation parameters, the detection of low-energy neutrinos coming from galactic core-collapse supernova, diffuse supernova background, the Sun, the Earth (geo-neutrinos) but also proton decay searches. This talk will give an overview on the JUNO physics potential and the current status of the project.
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HET Seminar
"Probing New Physics with Neutrino Scattering"
Presented by Ian Shoemaker, Virginia Tech
Wednesday, February 27, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Gopolang Mohlabeng
Current experimental sensitivities allow for neutrino scattering to be probed over a range of energy scales. In this talk, I'll discuss phenomenological probes of new physics using neutrino scattering at zero, GeV, and EeV momentum transfer. At zero momentum transfer, the forward coherent scattering of neutrinos on background particles provides novel sensitivity to Dark Matter. At MeV-GeV energies, the solar/atmospheric fluxes allow for the production of heavy sterile neutrinos at IceCube and direct detection experiments, resulting in distinctive signatures. Lastly, I'll discuss sterile neutrino scattering in the Earth as a possible explanation of the anomalous EeV events reported by ANITA.
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Physics Colloquium
"Precision measurement of neutrinos at Hyper-Kamiokande"
Presented by Akira Konaka, TRIUMF
Tuesday, February 26, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: George Redlinger
Hyper-Kamiokande (HyperK) is a water Cherenkov neutrino detector whose construction in Japan was recently approved. The fiducial mass is 187kton, eight times larger than the Super-Kamiokande detector. The upgraded J-PARC accelerator located 295km away will provide high intensity neutrino and anti-neutrino beams tuned at the oscillation maximum. In this talk, I will describe the challenges of the systematic uncertainties in future neutrino oscillation experiments and how HyperK plans to address them. In addition to the observation of CP violation, Hyper-Kamiokande will explore directions that may become the main research topic in the future if something new is discovered: Precision neutrino oscillations to test the unitarity of the lepton flavour mixing, neutrino astronomy, such as supernova neutrinos and searches for astrophysical point sources of neutrinos, and searches for phenomena beyond the standard model, such as dark matter and nucleon decays.
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Condensed-Matter Physics & Materials Science Seminar
"Unconventional superconductivity and complex tensor order in half-Heusler superconductors"
Presented by Igor Boettcher, University of Maryland
Tuesday, February 26, 2019, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Laura Classen
A revolutionary new direction in the field of superconductivity emerged recently with the synthesis of superconductors with strong inherent spin-orbit coupling such as the half-Heusler alloys. Due to band inversion, the low-energy degrees of freedom are electrons at a three-dimensional quadratic band touching point with an effective spin 3/2, which allows for higher-spin Cooper pairing and potentially topological superconductivity. I will illuminate some possibilities for unconventional superconductivity in this system, in particular a novel superconducting quantum critical point and the transition into a phase with complex tensor order, which is a superconducting state captured by a complex second-rank tensor valued order parameter describing Cooper pairs having spin 2. Here the interplay of both tensorial and complex nature results in a rich and intriguing phenomenology. I will highlight how optical response measurements can shed light on the phase structure of individual compounds.
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NT / RIKEN Seminar
"Quantum Chaos, Wormholes and the Sachdev-Ye-Kitaev Model"
Presented by Jacobus Verbaarschot, Stony Brook University
Friday, February 22, 2019, 2 pm
2-38 CFNS Seminar RoomHosted by: Niklas Mueller
The Sachdev-Ye-Kitaev (SYK) model has a long history in nuclear physics where its precursor was introduced as a model for the two-body nuclear interaction to describe the spectra of complex nuclei. Most notably, its level density is given by the Bethe formula and its level correlations are consistent with chaotic motion of the nucleons. Recently, this model received a great of attention as a solvable model for the quantum states of a black hole, exactly because of these properties. In this lecture we introduce the SYK model from a nuclear physics perspective and discuss its chaotic nature and its relation with black hole physics. We end with a summary of recent work on two SYK models coupled by a spin-spin interaction as a model for wormholes.
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Particle Physics Seminar
"Probing New Physics and the Nature of the Higgs Boson at ATLAS"
Presented by Lailin Xu, University of Michigan
Thursday, February 21, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The long-sought Higgs boson discovered at the LHC completes the Standard Model of the particle physics. During the last six years, substantial achievements have been made to probe the nature of the Higgs boson. Participle physics is however at an impasse: deep mysteries of the Electroweak symmetry breaking remain unanswered, and long-awaited new physics phenomena beyond the SM have not shown up yet. In this talk, I start with a brief overview on the current profile of measurements of the Higgs boson properties and couplings. I then present Higgs measurements in the four-lepton channel, and how we use the Higgs boson as a portal in the quest for new physics. In the end, I discuss the prospect of the Higgs measurements including the Higgs self-coupling at future colliders.
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Physics Colloquium
"Physics education research in higher education: What can we learn from the top cited papers in the Physical Review?"
Presented by Charles Henderson, Western Michigan University
Tuesday, February 19, 2019, 3:30 pm
Large Seminar Room, Bldg. 510The journal Physical Review Physics Education Research was started in 2005 as the archival research journal for the field of Physics Education Research (PER). In this talk I will identify some important findings from the field of PER based on highly cited articles from the journal. For example, there is strong evidence that in typical physics courses many students do not learn the core concepts of the discipline; student beliefs about physics become less expert like; and there is a significant gender gap, with men outperforming women. Many PER-based instructional strategies can improve student knowledge and some instructional strategies can improve student beliefs. However, implementation of these strategies is low because the field often uses ineffective dissemination strategies.
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Condensed-Matter Physics & Materials Science Seminar
": Electronic structure of d-metal systems as revealed by ab initio modeling of resonant inelastic X-ray scattering"
Presented by Lei Xu, Leibniz Institute for Solid State and Materials Research Dresden, Germany
Friday, February 15, 2019, 11 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Weiguo Yin
I will present our work on the theoretical investigation of the electronic structure, magnetic interactions and resonant inelastic X-ray scattering (RIXS) in 3d or 4d-5d transition metal (TM) compounds by using wave-function-based many-body quantum chemistry (QC) methods. My presentation contains two parts. In the first part, I will discuss the magnetic properties of 4d and 5d TM ions with a formally degenerate t12g electron configuration in the double-perovskite (DP) materials Ba2YMoO6, Ba2LiOsO6 and Ba2NaOsO6. Our analysis indicates that the sizable magnetic moments and g-factors found experimentally are due to both strong TM d – ligand p hybridization and dynamic Jahn-Teller effects. Our results also point out that cation charge imbalance in the DP structure allows a fine tuning of the gap between the t2g and eg levels. In another example of t12g electron configuration, spin-Peierls (SP) TiPO4 compound, we assign excitation peaks of experimental RIXS spectra and find that the d1 ground state is composed of an admixture of dz2 and dxz orbital character. In the second part, I will discuss a computational scheme for computing intensities as measured in X-ray absorption and RIXS experiments. We take into account the readjustment of the charge distribution in the 'vicinity' of an excited electron for the modeling of RIXS. The computed L3-edge RIXS spectra for Cu2+ 3d9 ions in KCuF3 and for Ni2+ 3d8 ions in La2NiO4 reproduce trends found experimentally for the incoming-photon incident-angle and polarization dependence.
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Particle Physics Seminar
"Measuring CCQE-like Cross Sections in MINERvA: when statistics meet precision"
Presented by Mateus F. Carneiro, Oregon State University
Thursday, February 14, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Elizabeth Worcester
MINERvA is a detector build to measure neutrino-nucleus cross sections. As we move towards more precise measurements, cross sections are of extreme importance to the future of neutrino physics. This talk will walk through all the steps necessary to simulate, select signal and measure a CCQE cross section while we test different nuclear models. New preliminary MINERvA results using the new configuration of the NuMI beam will be presented.
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RIKEN Lunch Seminar
"Chiral Photocurrents and Terahertz Emission in Dirac and Weyl Materials"
Presented by Mr. Sahal Kaushik, Stony Brook University
Thursday, February 14, 2019, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
Recently, chiral photocurrents have been observed in Weyl materials. We propose a new mechanism for photocurrents in Dirac materials in the presence of magnetic fields, that does not depend on any asymmetries of the crystal. This Chiral Magnetic Photocurrent would be an independent probe of the chiral anomaly. We also also discuss an observation of terahertz emission in the Weyl material TaAs with tunable ellipticity, due to chiral photocurrents induced by an ultrafast near infrared laser.
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Condensed-Matter Physics & Materials Science Seminar
"Resonant inelastic X-ray scattering (RIXS) as a probe of exciton-phonon coupling"
Presented by Andrey Geondzhian, European Synchrotron Radiation Facility (ESRF), France (UTC+1)
Thursday, February 14, 2019, 9:30 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Weiguo Yin
Phonons contribute to resonant inelastic X-ray scattering (RIXS) as a consequence of the coupling between electronic and lattice degrees of freedom. Unlike other techniques that are sensitive to electron-phonon interactions, RIXS can give access to momentum dependent coupling constants. This Information is highly desirable in the context of understanding anisotropic conventional and unconventional superconductivity. In my talk, I will consider the phonon contribution to RIXS from the theoretical point of view. In contrast to previous studies, we emphasize the role of the core-hole lattice coupling. Our model, with parameters obtained from first principles, shows that even in the case of a deep core-hole, RIXS probes exciton-phonon coupling rather than a direct electron-phonon coupling. Further, to address the needs of predictive approach and overcome limitations of the model studies we developed a Green's function formalism to capture electron-phonon contributions to RIXS and other core-level spectroscopies (X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS)). Our approach is based on the cumulant expansion of the Green's function combined with many-body theory calculated vibrational coupling constants. In the case of the XAS and RIXS, we use a two-particle exciton Green's function, which accounts implicitly for particle-hole interference effects that have previously proved difficult. Finally, to demonstrate the methodology, we successfully applied our formalism to small molecules, for which unambiguous experimental data exist.
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Condensed-Matter Physics & Materials Science Seminar
"Phase transition in functional materials and structural dynamics as studied by UTEM"
Presented by Ming Zhang, Institute of Physics, Chinese Academy of Sciences
Tuesday, February 12, 2019, 10 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Jing Tao
My presentation contains 3 parts. First, I will briefly introduce the pump-probe technique and Ultrafast Transmission Electron Microscopy (UTEM). Then I will demonstrate our development project of the UTEM, including the modifications of the configuration, the establishment of optical system, the generation of photoelectrons, and specific cases are discussed to show the capability of our UTEM. At last, I will highlight the application of UTEM via two examples: (1) The photoinduced martensitic (MT) transition and reverse transition in a shape memory alloy Mn50Ni40Sn10 have been examined by UTEM, and imaging and diffraction observations clearly show a variety of structural dynamic features at picosecond time scales; (2) The Lorentz UTEM for direct imaging photoinduced ultrafast magnetization dynamics, revealing remarkable features of magnetic transient states after a femtosecond pulsed laser excitation, and three successive dynamical processes involving four distinct magnetic states are evidently observed in MnNiGa crystals.
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NT / RIKEN Seminar
"Realizing relativistic dynamics with slow light polaritons at room temperature"
Presented by Eden Figueroa, Stony Brook University
Friday, February 8, 2019, 2 pm
CFNS Seminar RoomHosted by: Niklas Mueller
Experimental verification of relativistic field theory models requires accelerator experiments. A possible pathway that could help understanding the dynamics of such models for bosons or fermions is the use of quantum technology in the form of quantum analog simulators. In this talk we will explore the possibility of generating nonlinear Dirac-type Hamiltonians using coherent superpositions of photons and spin wave excitations of atoms. Our realization uses a driven slow-light setup, where photons mimic the Dirac fields and different dynamics can be implemented and tuned by adjusting optical parameters. We will show our progress tin building a quantum simulator of the Jackiw-Rebbi model using highly-interacting photons strongly coupled to a room temperature atomic ensemble. We have identified suitable conditions in which the input photons dispersion relations can be tuned to a spinor of light configuration, mimicking the Dirac regime and providing a framework to create tunable interactions and varying mass terms. Lastly, we will show our vision to scale these ideas to multiple interacting fermions.
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RIKEN Lunch Seminar
"Modification of the nucleon-nucleon potential and nuclear correlations due to the QCD critical point"
Presented by Juan M. Torres-Rincon, Stony Brook University
Thursday, February 7, 2019, 12 pm
Building 510, Room 2-160Hosted by: Enrico Rinaldi
The scalar-isoscalar mode of QCD becomes lighter/nearly massless close to the chiral transition/second-order critical point. This mode is the main responsible for the attractive part of the nucleon-nucleon potential at distances of 1-2 fm. Therefore, a long-range strong attraction among nucleons is predicted to develop close to the QCD critical point. Using the Walecka-Serot model for the NN potential we study the effects of the critical mode in a system of nucleons and mesons using a Molecular Dynamics+Langevin equations for the freeze-out conditions of heavy-ion collisions. Beyond mean field, we observe strong nucleon correlations leading to baryon clustering. We propose that light-nuclei formation, together with an enhancement of cumulants of the proton distribution can signal the presence of the QCD critical point.
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Condensed-Matter Physics & Materials Science Seminar
"Stimulation of quantum phases by time-dependent perturbations"
Presented by Victor Galitski, University of Maryland
Thursday, February 7, 2019, 11 am
ISB Bldg. 734, Conf. Room 201 (upstairs)Hosted by: Mark Dean
I will review our theory work on dynamic stimulation of various quantum phases. A key idea here is that the equilibrium distribution is rarely optimal for occurrence of a given quantum state and dynamic perturbations can be used to "deform" an electron population in a favorable way in order to enhance quantum coherence. To illustrate this idea, I will show how both Cooper pairing and phase coherence can be dynamically enhanced in both conventional superconductors and bosonic superlfuids. Then, I will discuss dynamic enhancement of high-temperature superconductivity in the cuprates, as it reported in experiments by the Andrea Cavalleri group in Hamburg. It will be shown that an optical pump can suppress charge order and simultaneously enhance superconductivity, due to the inherent competition between the two. In the second part of my talk, I will generalize these ideas to quantum cavities, where the light-matter coupling can be strongly enhanced. In particular, I will discuss the hybridization of cavity photons with collective modes in interacting two-dimensional materials, including the formation of Higgs polaritons and the closest analogue to excitons in a superconductor - Bardasis-Schrieffer modes - hybridized with light.
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Condensed-Matter Physics & Materials Science Seminar
"Novel Electrochemistry for Fuel Cell Reactions: Efficient Synthesis and New Characterization Methods"
Presented by Zhixiu Liang
Wednesday, February 6, 2019, 4:30 pm
Bldg. 480 Conference RoomHosted by: Jing Tao
The ever increasing consumption of fossil fuels for transportation causes climate change causing a growing concern about their future availability and further adverse environmental effects. To address this issue, the concept of CO2 neutral fuels-based energy cycle was brought out. The key reactions in that concept are electrochemical methanol oxidation (MOR), ethanol oxidation reaction (EOR), and CO2 reduction reaction (CO2RR). These all are elctrocatalysis research challenges being slow even at the best catalyst that hamper application of fuel cells, and bring environmental benefits. My research made these improvements of catalysts for the key reactions. In-situ electrochemical infrared reflective absorbance spectrum (EC-IRRAS) reveals that at lower temperature, such reaction is not complete and generates more formate; at elevated temperature, such reaction is complete to carbonate. Ethanol is one of the ideal fuels for fuel cells, but requires highly improved catalysts. Au@PtIr/C catalyst was synthesized with a surfactant-free wet-chemistry approach. Transmission electron microscope (TEM) characterization confirms the monolayer/sub-monolayer Pt-Ir shell, gold core structure. The catalyst has a very high mass activity of 58 A/mg at peak current. In situ EC-IRRAS reveals that C-C bond is cleaved upon contact with the catalyst surface leading to ethanol complete oxidation to CO2. Related researches on methodologies, included in situ TEM to help obtaining catalysts improvements, give morphologic, structural and spectroscopic information at wide range from hundreds of microns to sub-nanometer coupled with various detectors. Microelectromechanical System (MEMS) based chips technology enables TEM observation in operando, with liquid-flow-cell chips and electrochemistry chips designed and fabricated. Ag@Au hollow cubes synthesis via galvanic replacement of Au on Ag cubes was investigated with in situ TEM. The results demonstrate abnormal react
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HET Seminar
"Searching for flavour symmetries: old data new tricks"
Presented by Jessica Turner, Fermilab
Wednesday, February 6, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Gopolang Mohlabeng
The observed pattern of mixing in the neutrino sector may be explained by the presence of a non-Abelian, discrete flavour symmetry broken into residual subgroups at low energies. These flavour models require the presence of Standard Model singlet scalars, namely flavons, which decay to charged leptons in a flavour-conserving or violating manner. In this talk, I will present the constraints on the model parameters of an A4 leptonic flavour model using a synergy of g-2, charged lepton flavour conversion and collider data. The most powerful constraints derive from the MEG collaboration's result and the reinterpretation of an 8 TeV ATLAS search for anomalous productions of multi-leptonic final states.
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Nuclear Physics Seminar
"Probing the Sea Quark Polarization at RHIC/STAR"
Presented by Jinlong Zhang, Stony Brook University
Tuesday, February 5, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Oleg Eyser
Polarized proton-proton collision experiments at RHIC have provided unique opportunities to study the spin structure of the nucleon. One of the primary motivations of RHIC spin program is to probe sea quark spin-flavor structure via W-boson production in proton-proton collisions at a center of mass energy of 500 GeV. Measurements of the longitudinal single-spin asymmetry, A_L, of W-bosons with the STAR detector have provided significant constraints on the polarized parton distribution functions and especially the first experimental indication of a flavor asymmetry of polarized sea. In this seminar, I will present the analyses and latest results from STAR, as well as their impact on our knowledge of the sea quark helicity distributions.
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RIKEN Lunch Seminar
"Sorting out jet quenching in heavy-ion collisions"
Presented by Jasmine Brewer, Massachusetts Institute of Technology
Thursday, January 31, 2019, 12 pm
Building 510, Room 2-160Hosted by: Enrico Rinaldi
We introduce a new "quantile'' analysis strategy to study the modification of jets as they traverse through a droplet of quark-gluon plasma. To date, most jet modification studies have been based on comparing the jet properties measured in heavy-ion collisions to a proton-proton baseline at the same reconstructed jet transverse momentum pT. It is well known, however, that the quenching of jets from their interaction with the medium leads to a migration of jets from higher to lower pT, making it challenging to directly infer the degree and mechanism of jet energy loss. Our proposed quantile matching procedure is inspired by (but not reliant on) the approximate monotonicity of energy loss in the jet pT. In this strategy, jets in heavy-ion collisions ordered by pT are viewed as modified versions of the same number of highest-energy jets in proton-proton collisions. Despite non-monotonic fluctuations in the energy loss, we use an event generator to validate the strong correlation between the pT of the parton that initiates a heavy-ion jet and the pT of the vacuum jet which corresponds to it via the quantile procedure. We demonstrate that this strategy both provides a complementary way to study jet modification and mitigates the effect of pT migration in heavy-ion collisions.
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Environmental & Climate Sciences Department Seminar
"What can we learn from cloudy convection in a box? Laboratory meets LES with cloud microphysics"
Presented by Raymond Shaw, MTU
Thursday, January 31, 2019, 11 am
Conference Room Bldg 815EHosted by: Fan Yang
Inspired by early convection-tank experiments (e.g., Deardorff and Willis) and diffusion-chamber experiments, we have developed a cloud chamber that operates on the principle of isobaric mixing within turbulent Rayleigh-Bénard convection. The "Pi cloud chamber" has a height of 1 m and diameter of 2 m. An attractive aspect of this approach is the ability to make direct comparison to large eddy simulation with detailed cloud microphysics, with well characterized boundary conditions, and statistical stationarity of both turbulence and cloud properties. Highlights of what we have learned are: cloud microphysical and optical properties are representative of those observed in stratocumulus; aerosol number concentration plays a critical role in cloud droplet size dispersion, i.e., dispersion indirect effect; aerosol-cloud interactions can lead to a condition conducive to accelerated cloud collapse; realistic and persistent mixed-phase cloud conditions can be sustained; LES is able to capture the essential features of the turbulent convection and warm-phase cloud microphysical conditions. It is worth considering what more could be learned with a larger-scale cloudy-convection chamber. Turbulence Reynolds numbers and Lagrangian-correlation times would be scaled up, therefore allowing more enhanced role of fluctuations in the condensation-growth process. Larger vertical extent (of order 10 m) would approach typical collision mean free paths, thereby allowing for direct observation of the transition from condensation- to coalescence-growth. In combination with cloudy LES, this would be an opportunity for microphysical model validation, and for synergistic learning from model-measurement comparison under controlled experimental conditions.
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HET Seminar
"Matrix Elements for Neutrinoless Double Beta Decay from Lattice QCD"
Presented by David Murphy, MIT
Wednesday, January 30, 2019, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Aaron Meyer
While neutrino oscillation experiments have demonstrated that neutrinos have small, nonzero masses, much remains unknown about their properties and decay modes. One potential decay mode —- neutrinoless double beta decay ($0 \nu \beta \beta$) —- is a particularly interesting target of experimental searches, since its observation would imply both the violation of lepton number conservation in nature as well as the existence of at least one Majorana neutrino, in addition to giving further constraints on the neutrino masses and mixing angles. Relating experimental constraints on $0 \nu \beta \beta$ decay rates to the neutrino masses, however, requires theoretical input in the form of non-perturbative nuclear matrix elements which remain difficult to calculate reliably. In this talk we will discuss progress towards first-principles calculations of relevant nuclear matrix elements using lattice QCD and effective field theory techniques, assuming neutrinoless double beta decay mediated by a light Majorana neutrino.
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Condensed-Matter Physics & Materials Science Seminar
"Strongly-correlated systems: Controllable field-theoretical approach"
Presented by Igor Tupitsyn, University of Massachusetts Amherst
Tuesday, January 29, 2019, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Alexei Tsvelik
Accurate account for interactions in theoretical models for strongly correlated many-body systems is the key for understanding real materials and one of the major technical challenges of modern physics. To accept this challenge, new and more effective methods, capable of dealing with interacting systems/models in an approximation-free manner, are required. One of such methods is the field-theoretical Diagrammatic Monte Carlo technique (DiagMC). While a conventional Quantum Monte Carlo samples the configuration space of a given model Hamiltonian, the DiagMC samples the configuration space of the model-specific Feynman diagrams and obtains final results with controlled accuracy by accounting for all the relevant diagrammatic orders. In contrast to conventional QMC, it does not suffer from the fermionic sign problem and can be applied to any system with arbitrary dispersion relation and shape of the interaction potential (both doped and undoped). In the first part of my talk I will introduce the technique, based on its bold-line (skeleton) implementation, and benchmark it against known results for the problem of semimetal-insulator transition in suspended graphene. In the second part I will briefly demonstrate its applications to various strongly-correlated systems/problems (stability of the 2d Dirac liquid state against strong long-range Coulomb interaction; interacting Chern insulators; phonons in metals; 1d chain of hydrogen atoms; uniform electron gas (jellium model), optical conductivity, etc).
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Nuclear Physics Seminar
"Measurements and Calculations of $\hat{q}L$ via transverse momentum broadening in RHIC collisions using di-hadron correlations"
Presented by Michael Tannenbaum, BNL
Tuesday, January 29, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
The renewed interest in analyzing RHIC data on di-hadron correlations as probes of final state transverse broadening as shown at Quark Matter 2018 by Miklos Gyulassy citing theoretical calculations compared to experimental measurements which didn't look right on Miklos' figure led me to take a closer look at this issue using published PHENIX data . The measured values of $\hat{q}L$ show the interesting effect of being consistent with zero for values of the associated particle transverse momentum pTa >3 GeV/c. This is shown to be related to the well-known effect of the variable IAA, the ratio of the Au+Au to p+p pTa distributions for a given trigger pTt.
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Nuclear Theory / RIKEN Seminar
"Effective field theory of hydrodynamics"
Presented by Paolo Glorioso, Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago
Friday, January 25, 2019, 2 pm
CFNS Seminar Room 2-38Hosted by: Niklas Mueller
I will give an overview of our work on developing an effective field theory of dissipative hydrodynamics. The formulation is based on the Schwinger-Keldysh formalism, which provides a functional approach that naturally includes dissipation and fluctuations. Hydrodynamics is implemented by introducing suitable degrees of freedom and symmetries. I will then discuss two important by-products. First, the second law of thermodynamics, which in the traditional approach is imposed at phenomenological level, is here obtained from a basic symmetry principle together with constraints from unitarity. Second, I will show consistency with unitarity and causality of the hydrodynamic path-integral at all loops, which leads to the first systematic framework to compute hydrodynamic fluctuations.
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RIKEN Lunch Seminar
"Quarkonium production in heavy ion collisions: open quantum system, effective field theory and transport equations"
Presented by Xiaojun Yao, Duke University
Thursday, January 24, 2019, 12 pm
Building 510, Room 1-224Hosted by: Yuta Kikuchi
In this talk, I will present a connection between two approaches of studying quarkonium dynamics inside quark-gluon plasma: the open quantum system formalism and the transport equation. I will discuss insights from the perspective of quantum information. I will show that under the weak coupling and Markovian approximations, the Lindblad equation turns to a Boltzmann transport equation after a Wigner transform is applied to the system density matrix. I will demonstrate how the separation of physical scales justifies the approximations, by using effective field theory of QCD. Finally, I will show some phenomenological results based on the derived transport equation.
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Instrumentation Division Seminar
"A Roadmap for the Best PMTs and SiPM in Physics Research"
Presented by Razmik Mirzoyan, Max Planck Institute for Physics, Germany
Wednesday, January 23, 2019, 2:30 pm
Large Conference Room, Bldg. 535Photomultiplier Tubes (PMT) are the most wide spread detectors for measuring fast and faint light signals. In cooperation with the companies Hamamatsu Photonics K.K. (Japan) and Electron Tubes Enterprises Ltd. (England) we pursued an improvement program for the PMTs for the Cherenkov Telescope Array (CTA) project. CTA is the next major Imaging Atmospheric Cherenkov Telescopes (IACT) array for ground-based very high energy gamma-ray astrophysics. A total of ∼100 telescopes of sizes of 23m, 12m and 4m in diameter will be built in northern and southern hemispheres. The manufacturers succeeded producing 1.5′ PMTs of enhanced peak quantum efficiency of ∼38-42 % and after pulsing below 0.02% (threshold ≥ 4 photoelectrons). The novel 1.5′ PMTs have the world-wide best parameters. It is interesting to compare the performance of PMTs with the current generation of SiPMs. In the imaging camera of the MAGIC IACT, consisting of 1039 PMTs, since many months we are operating composite clusters of SiPMs from the three well-known manufacturers. A critical comparison of these two types of sensors will be presented. Prospects for further significant improvements of PMTs and SiPMs will be discussed, also in the frame of the supported by the EU SENSE Roadmap for the best fast light sensors.
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Condensed-Matter Physics & Materials Science Seminar
"Recent Progress in Non-perturbative methods for QFTs"
Presented by Lorenzo Vitale, Boston University
Wednesday, January 23, 2019, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Alexei Tsvelik
Quantum field theories (QFT) are notoriously hard to solve in the strongly coupled regime, and few tools are available in space dimension larger than one. In this talk I discuss recent progress and ideas in characterizing certain QFTs in dimension d >= 1, based on the Hamiltonian Truncation and S-matrix bootstrap techniques. Some of the applications I will mention are Landau-Ginzburg theories and the Chern-Simons-matter theories.
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Particle Physics Seminar
"Exploring the HEP frontier with the Cosmic Microwave Background and 21cm cosmology"
Presented by Laura Newburgh, Yale University
Friday, January 18, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Anze Slosar
Current cosmological measurements have left us with deep questions about our Universe: What caused the expansion of the Universe at the earliest times? How many standard model particles are there? What is the underlying nature of Dark Energy and dark matter? New experiments like CMB-StageIV, Simons Observatory, and CHIME are poised to address these questions through measurements of the polarized Cosmic Microwave Background and 3-dimensional maps of structure. In this talk, I will describe efforts in the community to deploy enormous experiments that are capable of turning CMB measurements into probes of high energy particle physics. I will also discuss how we can broaden the potential science returns by including 21 cm measurements of large scale structure as a new means to probe Dark Energy with experiments like CHIME and HIRAX.
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Nuclear Theory / RIKEN Seminar
"Chiral Vortical Effect For An Arbitrary Spin"
Presented by Andrey Sadofyev, Los Alamos National Lab
Friday, January 18, 2019, 2 pm
CFNS Seminar Room 2-38Hosted by: Niklas Mueller
Chiral effects attracted significant attention in the literature. Recently, a generalization of chiral vortical effect (CVE) to systems of photons was suggested. In this talk I will discuss the relation of this new transport to the topological phase of photons and show that, in general, CVE can take place in rotating systems of massless particles with any spin.
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Instrumentation Division Seminar
"Timing circuits for high-energy physics applications"
Presented by Jeffrey Prinzie, KU Leuven University, Belgium
Friday, January 18, 2019, 11 am
Large Conference Room, Bldg. 535In the era of complex systems on chip (SoCs), clock and timing generation is required in nearly any application. These timing generators supply clock signals to digital modules, act as heartbeats for serial communication links or provide picosecond accurate reference information to time-interval sensors. Phase Locked Loops are the main building block that provide clock signals. However, in the high-energy physics community, ionizing radiation effects degrade these circuits significantly and produce soft-errors which can disturb an entire system. In this seminar, the application of these timing blocks in the high-energy physics are discussed together with the mitigation techniques for ionizing radiation.
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RIKEN Lunch Seminar
"Proton decay matrix elements on lattice"
Presented by Mr. Jun-sik Yoo, Stony Brook University
Thursday, January 17, 2019, 12 pm
Building 510, Room 2-160Hosted by: Enrico Rinaldi
Proton decay is one of possible signatures of baryon number violation, which has to exist to explain the baryon asymmetry and the existence of nuclear matter. Proton decay is one of natural implications of the Grand Unification Theory. After integrating out the high energy degrees of freedom, the baryon number violation operator that mediates proton decay can be found as the composite operator of standard model fields. We discuss the hadronic matrix elements of this BV operator made of three quarks and a lepton. We will start from the current experimental bound of proton lifetime. We present preliminary results of matrix element calculation done with the 2+1 dynamical flavor domain wall fermions at the physical point. We will discuss the proton decay channels that no matrix element has been calculated on the lattice.
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Condensed-Matter Physics & Materials Science Seminar
"Effect of ion irradiation on the mechanical behavior and microstructural evolution of nanoscale metallic alloys"
Presented by Gowtham Sriram Jawaharram, University of Illinois at Urbana - Champaign
Wednesday, January 16, 2019, 11 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Jing Tao
Nanostructured alloys are considered as potential candidates for next generation (Generation IV) nuclear reactors because the high densities of interfacial defect sinks present in these materials. The effect of irradiation on the mechanical behavior of such alloys has received limited attention, likely resulting from the experimental challenges associated with performing such experiments. The first part of the talk will report on our recent efforts to perform high temperature irradiation induced creep (IIC) measurements in focused ion beam fabricated FCC alloys (single crystalline Ag nanopillars and nanocrystalline high entropy alloys (HEA) microbeams) by combining in-situ TEM based small-scale mechanical testing with ion irradiation and in-situ laser heating using the in-situ ion irradiation transmission electron microscope (I3TEM) at Sandia National Laboratories. The effect of pillar size, grain size, and temperature on the observed creep mechanism will be discussed. The second part of the talk will focus on the microstructural evolution of model highly immiscible CuW alloys during thermal annealing and high temperature irradiation characterized using high angle annular dark field (HAADF) imaging. The results will be discussed from the context of evolution and spatial distribution of W precipitates and its effect on hardness as a function of irradiation dose and temperature.
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Physics Colloquium
"Liquid Argon Detectors and Readout Electronics: From R&D to Physics Discovery"
Presented by Hucheng Chen, BNL
Tuesday, January 15, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Andrei Nomerotski
BNL has a long history of R&D in noble liquid based detectors, from the invention of the first liquid argon (LAr) calorimeter in 1974, to the construction of large liquid argon time projection chambers (LAr TPC) leading to Deep Underground Neutrino Experiment (DUNE) by 2026, in a time span over half a century. Readout electronics has always been an integral part of the detector, in both ATLAS LAr Calorimeter where high precision has played an essential role in the 2012 Higgs discovery, and in LAr TPC based neutrino detectors where cryogenic electronics proved to be an enabling technology. The development of noble liquid based detectors and readout electronics systems at BNL will be presented, focused on integrated detector-readout design, as motivated by our physics interests and experiment requirements, in energy frontier LHC experiments, and in intensity frontier short baseline and long baseline neutrino experiments. As both experiments present challenges in data acquisition, the FELIX based DAQ system for high-bandwidth detector readout developed at BNL, also being adopted in various particle physics experiments worldwide, will be discussed as well.
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Particle Physics Seminar
"Cross section measurements and new physics searches with WZ vector boson scattering events at CMS"
Presented by Kenneth Long, University of Wisconsin - Madison
Thursday, January 10, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricolli
As the standard model (SM) Higgs boson looks increasingly like its SM expectation, expanded tests of the electroweak (EW) sector of the SM are a focal point of the long-term LHC program. Production of massive vector bosons via vector boson scattering provides a direct probe of the self-interactions of the massive vector bosons, which are intimately connected to the Higgs-Englert-Brout mechanism of EW symmetry breaking. A search for vector boson scattering of W and Z bosons has recently been performed by the CMS experiment using data collected in 2016. I will present this search as well as WZ cross section measurements, which are less dependent on theoretical inputs. This process is also sensitive to New Physics in the EW sector. I will present interpretations of these results in terms of explicit models predicting additional charged Higgs bosons and in the generalized framework of dimension-8 effective field theory.
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Condensed-Matter Physics & Materials Science Seminar
"Exact Solution and Semiclassical Analysis of BCS-BEC Crossover in One Dimension"
Presented by Tianhao Ren, Columbia University
Monday, January 7, 2019, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Alexei Tsvelik
In this talk, I will introduce a new type of model for two-component systems in one dimension subject to exact solutions by Bethe ansatz. It describes the BCS-BEC crossover in one dimension and its integrability is obtained by fine-tuning the model parameters. The new model has rich many-body physics, where the Fermi momentum for the ground state distribution is constrained to be smaller than a certain value and the zero temperature phase diagram with an external field has a critical field strength for polarization. Also the low energy excitation spectra of the new model present robust features that can be related to solitons at BCS-BEC crossover in one dimension, as shown by the semiclassical analysis.
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Particle Physics Seminar
"DM-Ice17 and COSINE-100 NaI(Tl) Dark Mater Experiment: Testing DAMA's Claim for a Dark Matter Discovery"
Presented by Jay Hyun Jo, Yale University
Thursday, January 3, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
Astrophysical observations give overwhelming evidence for the existence of dark matter, yet we do not know what it is. For over 20 years, the DAMA collaboration has asserted that they observe a dark matter-induced annual modulation signal but their observation has yet to be confirmed by an independent measurement. DM-Ice17 is a prototype experiment consisting of 17 kg of NaI(Tl) detectors to test the DAMA's claimed detection of the dark matter annual modulation, which has been continuously operating at the South Pole since 2011. COSINE-100 is a joint experiment between DM-Ice and KIMS collaboration, situated at the Yangyang Underground Laboratory in South Korea. COSINE-100 consists of eight low background NaI(Tl) crystals with a total mass of 106 kg and 2000 liters of liquid scintillator as an active veto, and the physics run of the experiment began in September 2016. The recent results from DM-Ice17 and COSINE-100, including the status of the field, will be presented.
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Instrumentation Division Seminar
"Data Acquisition Systems for High-Speed and High-Dynamic Range Pixel Array Detectors"
Presented by Prafull Purohit, Cornell University
Friday, December 28, 2018, 10:30 am
Large Conference Room, Bldg. 535Pixel array detectors (PADs) have seen significant increase in performance and operational complexity in recent years due to advances in microelectronics technology and photon science needs. These advances in detector technology put equal complexity and performance requirements on the data acquisition and control systems for successful operation. A Field Programmable Gate Array (FPGA) with its high-speed processing and reconfiguration capabilities can be utilized to meet current requirements and future needs. In this talk, I will present some of the recent work done at Cornell University on FPGA-based data acquisition systems for high-speed, high dynamic range detectors as well as detectors for time resolved experiments.
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Particle Physics Seminar (Leona Woods Distinguished Postdoctoral Lectureship Award)
"Measurement of top quark pair production in association with a Higgs or gauge boson at the LHC with the ATLAS detector"
Presented by María Moreno Llácer, CERN
Thursday, December 20, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The top quark is unique among the known quarks since it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. Given its large mass (the heaviest fundamental particle), the top quark may play a special role in the electroweak symmetry breaking mechanism and therefore, new physics related to this might be found first in top quark precision measurements. Possible new physics signals would cause deviations of the top quark couplings from the Standard Model (SM) prediction. It couples to the SM fields through its gauge and Yukawa interactions. The high statistics top quark sample at the LHC has allowed to access the associated production of a top quark pair with a boson: tt+photon, tt+W, tt+Z and tt+H. The latest measurements carried out by the ATLAS detector for these physics processes will be presented, highlighting the main challenges.
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Physics Colloquium (Leona Woods Distinguished Postdoctoral Lectureship Award)
"On top of the top: challenging the Standard Model with precise measurements of top quark properties"
Presented by María Moreno Llácer, CERN
Tuesday, December 18, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Andrei Nomerotski
The understanding of the Electro-Weak Symmetry Breaking mechanism and the origin of the mass of fundamental particles is one of the most important questions in particle physics today. The top quark is unique among the known quarks since it is the heaviest fundamental particle in the Standard Model. Its large mass makes the top quark very different from all other particles, with a Yukawa coupling to the Higgs boson close to unity. For these reasons, the top quark and the Higgs boson play very special roles in the SM and in many extensions thereof. An accurate knowledge of their properties can bring key information on fundamental interactions at the electroweak breaking scale and beyond. The Large Hadron Collider is providing an enormous dataset of proton-proton collisions at the highest energies ever achieved in a laboratory. With the unprecedentedly large sample of top quarks, a new frontier has opened, the flavour physics of the top quark, allowing to study whether the Higgs field is the unique source of the top quark's mass and whether there are unexpected interactions between the top quark and the Higgs boson. The answers to these questions will shed light on what may lie beyond the Standard Model and can even have cosmological implications.
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Condensed-Matter Physics & Materials Science Seminar
"Uncovering the interactions behind quantum phenomena"
Presented by Keith Taddei, Oak Ridge National Laboratory
Tuesday, December 18, 2018, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson/Mark Dean
Quantum computing, spintronics and plasmonics are nascent fields with potential to radically change our technological landscape. Fundamental to advancing these technologies is a mastery of quantum materials such as superconductors, quantum-spin-liquids and multiferroics. Ideally, we would know exactly what interactions give rise to these phenomena and design materials suitable for applications however, such an understanding as of yet eludes us. Instead we are stuck digging around in the phase space of known quantum materials slowly uncovering pertinent details to their design, filling in pieces of our incomplete picture. In this presentation, I will discuss recent bits I have found in my use of neutron scattering to study quantum materials. Starting with a novel new family of quasi-one-dimensional (Q1D) superconductors (A1,2TM3As3 with A = alkali metal and TM = Cr, Mo) I will present findings of short-range structural order and a proximate magnetic instability which, due the radically different structure, allow for new insights to the pertinence to such orders to superconductivity. Importantly, in these materials the two orders break different symmetries and so their interactions with the superconducting order can be studied independently. Next, I will discuss an interesting yet neglected family of frustrated magnetic materials – the rare-earth pyrogermanates (REPG). We find the Er2Ge2O7 REPG to exhibit 'local-Ising' type magnetism in direct analogy to the spin-ice pyrochlores suggesting effects of local anisotropies and dipole interactions. Finally, I will present ongoing work investigating spin-driven polarization effects in the magnetically and structurally straightforward multiferroic BiCoO3. These results demonstrate the essential role of neutron and x-ray scattering techniques in studying these complex materials and the fruitful opportunities these systems present to advance our understanding of quantum materials.
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Physics Colloquium
"The Science of the Sudbury Neutrino Observatory (SNO) and SNOLAB"
Presented by Art McDonald, Queens University
Monday, December 17, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: David Asner
A description of the science associated with the Sudbury Neutrino Observatory, performed with substantial contributions from BNL scientists, and its relation to other neutrino measurements will be given, along with a discussion of the new set of experiments that are at various stages of development or operation at SNOLAB. These experiments will perform measurements of neutrino properties and seek direct detection of Weakly-Interacting Massive Particles (WIMPS) as Dark Matter candidates. Specific examples will include SNO+ (with BNL participation), in which the central element of the SNO detector will now be liquid scintillator with Te dissolved for neutrino-less double beta decay and DEAP-3600 using liquid argon for single phase direct Dark Matter detection. Future directions for Dark Matter detection with liquid argon will also be discussed.
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NT/RIKEN Seminar
"Lattice QCD Input for Fundamental Symmetry Tests"
Presented by Micheal Wagman, MIT
Friday, December 14, 2018, 2 pm
Building 510, Room 2-38Hosted by: Niklas Mueller
Experimental detection of fundamental symmetry violation would provide a clear signal for new physics, but theoretical predictions that can be compared with data are needed in order to interpret experimental results as measurements or constraints of beyond the Standard Model physics parameters. For low-energy experiments involving protons, neutrons, and nuclei, reliable theoretical predictions must include the strong interactions of QCD that confine quarks and gluons. I will discuss experimental searches for neutron-antineutron oscillations that test beyond the Standard Model theories of matter-antimatter asymmetry with low-scale baryon-number violation. Lattice QCD can be used to calculate the neutron-antineutron transition rate using a complete basis of six-quark operators describing neutron-antineutron oscillations in effective field theory, and I will present the first lattice QCD results for neutron-antineutron oscillations using physical quark mass simulations and fully quantified uncertainties. Other experiments searching for neutrinoless double-beta decay and dark matter direct detection use large nuclear targets that are more difficult to simulate in lattice QCD because of an exponentially difficult sign(al-to-noise) problem. I will briefly describe the state-of-the-art for lattice QCD calculations of axial, scalar, and tensor matrix elements relevant to new physics searches with nuclei and outline my ongoing efforts to improve signal-to-noise problems using phase unwrapping.
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Condensed-Matter Physics & Materials Science Seminar
"Discussion of opportunities related to Quantum Information initiative"
Presented by Alexei Tsvelik, BNL
Friday, December 7, 2018, 3 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Alexei Tsvelik will be sharing his thoughts on how we can answer to the DOE initiative on Quantum Information
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NSLS-II Friday Lunchtime Seminar
"Magnetic skyrmions at room temperature - statics, dynamics, and high resolution imaging"
Presented by Dr. Felix Buttner, Dept of Mat Sci & Eng , MIT
Friday, December 7, 2018, 12 pm
NSLS-II Bldg 743 Room 156Hosted by: Ignace Jarrige
Magnetic skyrmions are the smallest non-trivial entities in magnetism with great potential for data storage applications. These chiral and topological quasi-particles furthermore exhibit fascinating static and dynamical properties that render them the ideal candidates to study new physics in high spin-orbit coupling materials. In this talk, I will first give a general introduction to the field of skyrmionics and the fundamental properties of skyrmions that derive from their energetics. I will then discuss various ways of creating and stabilizing room-temperature skyrmions experimentally, as well as how we can move them and observe their topological dynamics via high resolution time-resolved x-ray imaging. I will conclude with perspectives of future research in this field and related areas.
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Particle Physics Seminar
"The Global Electroweak Fit in the light of the new results from the LHC"
Presented by Matthias Schott, University of Mainz
Thursday, December 6, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
With the high integrated luminosities recorded at the LHC and the very good understanding of the LHC detectors, it is possible to measure electroweak observables to the highest precision. In this talk, I review the measurement of the W boson mass as well as the measurement of the electroweak mixing angle with the ATLAS detector, both achieving highest precision after several years of intense effort. Special focus is drawn on a discussion of the modeling uncertainties as well as the physics potential of the latest low-mu runs, recorded at in 2017 and 2018. The results will be interpreted in terms of the overall consistency of the Standard Modell by the global electroweak fit, performed by the Gfitter Collaboration.
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Condensed-Matter Physics & Materials Science Seminar
"Laser induces dynamics in complex oxides with visible/NIR and X-ray probe (Note: This will be a skype presentation)"
Presented by Sergii Parchenko, Swiss Light Source, Paul Scherrer Institute, Switzerland
Tuesday, December 4, 2018, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson/Mark Dean
**********Note: This will be a Skype Presentation************ recent achievements in generation of ultrashort and intense light pulses allow observation of the physical process on the ultrafast regime. exploring fundamental physical processes on the time scales of interactions, responsible for them, is the key for future understanding of the physical principles and implementation then to the technological application. with this talk, i'm going to present the study of laser induced dynamics in complex oxides with focus on several physical objects: magnetic exchange interaction, insulator to metal transition and magneto-electric coupling. it will be discussed how the study of laser induced changes with different probing methods could help to understand the microscopic mechanisms of physical processes on the ultrafast time scale.
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Condensed-Matter Physics & Materials Science Seminar
"First-principles description of correlated materials with strong spin-orbit coupling: the analytic continuation and branching ratio calculation"
Presented by Jae-Hoon Sim, Department of Physics, KAIST, Korea, Republic of (South)
Monday, December 3, 2018, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Sangkook Choi
The DFT+DMFT combined with the continuous-time quantum Monte Carlo (CT-QMC) impurity solver is one of the successful approaches to describe correlated electron materials. However, analytic continuation of the QMC data written in the imaginary frequency to the real axis is a difficult numeric problem mainly due to the ill-conditioned kernel matrix. While the maximum entropy method is one of the most suitable choices to gain information from the noisy input data, its applications to the materials with strong spin-orbit coupling are limited by the non-negative condition of the output spectral function. In the first part of this talk, I will discuss the newly developed methods for analytic continuation problem, the so-called maximum quantum entropy method (MQEM) [1]. It is the extension of the conventional method, introducing quantum relative entropy as a regularization function. The application of the MQEM for a prototype j_eff=1/2 Mott insulator, Sr2IrO4, shows that it provides a reasonable band structure without introducing a material specific base set. I will also introduce the application of machine learning technique to the same problem [2]. In the second part, a simple technique to branching ratio from the first-principles calculation will be discussed [3]. The calculated ?L·S? and branching ratio of the different 5d iridates, namely Sr2IrO4, Sr2MgIrO6, Sr2ScIrO6, and Sr2TiIrO6 are in good agreement with recent experimental data. Its reliability and applicability also be carefully examined in the recent study. [1] J.-H. Sim and M. J. Han, Phys. Rev. B 98, 205102 (2018). [2] H. Yoon, J.-H. Sim, and M. J. Han, Phys. Rev. B (in press). [3] J.-H. Sim, H. Yoon, S. H. Park, and M. J. Han, Phys. Rev. B 94, 115149 (2016).
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Condensed-Matter Physics & Materials Science Seminar
"Localized-to-itinerant crossovers in Kondo materials"
Presented by Daniel Mazzone, Brookhaven National Laboratory, NSLS-II
Monday, December 3, 2018, 11 am
ISB Bldg. Conf. Room 201 (upstairs)Hosted by: Ian Robinson/Mark Dean
While charge carriers in crystalline structures can be located close to the nuclei or establish a delocalized character, they often epitomize strong fluctuations at intermediate regimes where emergent quantum phases show an intricate coupling among various degrees of freedom. Kondo materials are particularly interesting model systems to investigate strongly correlated phenomena, because they often possess small energy scales that are highly susceptible to macroscopic constraints. I will present recent neutron and X-ray scattering results on the series Nd1-xCexCoIn5 and Sm1-xYxS, where the ground state properties were tuned either via chemical substitution or magnetic field. We find that Nd substitution in CeCoIn5 affects the magnetic coupling parameters, triggering a change in the magnetic symmetry that is offset from the emergence of coherent heavy bands and unconventional superconductivity. Intriguingly, another magneto-superconducting phase with altered coupling is observed in Nd0.05Ce0.95CoIn5 at large magnetic fields. Sm1-xYxS features a transition towards an intermediate valence state under yttrium doping. Our results unravel a Kondo-triggered Lifshitz-transition in the mixed-valence state, which dives an unusually strong charge localization at low temperatures.
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Nuclear Theory / RIKEN Seminar
"Novel probes of small-x QCD"
Presented by Juan Rojo, VU University
Friday, November 30, 2018, 2 pm
CFNS Seminar Room 2-38Hosted by: Niklas Mueller
The small Bjorken-x regime of QCD is of great interest since a variety of different phenomena are known or expected to emerge, from BFKL small-x effects and non-linear and saturation dynamics to shadowing corrections in heavy nuclei. In this talk we present recent developments in our understanding of perturbative and non-perturbative QCD at small-x: the evidence for BFKL dynamics in the HERA structure function data, the precision determination of collinear PDFs from charm production at LHCb, and the first results on neural-network based fits of nuclear PDFs. We also highlight the remarkable connection between small-x QCD and high-energy astrophysics, in particular for the theoretical predictions of signal and background event rates at neutrino telescopes such as IceCube and KM3NET
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Particle Physics Seminar
"The structure of the proton in the LHC precision era"
Presented by Juan Rojo, Vrije Universiteit Amsterdam and Nikhef
Thursday, November 29, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The determination of the partonic structure of the proton is a central component of the precision phenomenology program at the Large Hadron Collider (LHC). This internal structure of nucleons is quantified in the collinear QCD factorization framework by the Parton Distribution Functions (PDFs), which encode the probability of finding quarks and gluons inside the proton carrying a given amount of its momentum. PDFs cannot currently be computed from first principles, and therefore they need to be determined from experimental data from a variety of hard-scattering cross-sections in lepton-proton and proton-proton collisions. This program, known as the global QCD analysis, involves combining the most PDF-sensitive data and the highest precision QCD and electroweak calculations available within a statistically robust fitting methodology. In this talk I review our current understanding of the quark and gluon structure of the proton, which emphasis for the implications for precision LHC phenomenology and searches for new physics, but also exploring other aspects of the nucleon structure such as their impact on high-energy neutrino telescopes, the connection with lattice QCD calculations, and the onset of novel small-x dynamics beyond the collinear framework. Finally, I highlight the prospects for improving our understanding of the quark/gluon structure of the nucleon at the high-luminosity LHC era.
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HET Seminar
"FASER: ForwArd Search ExpeRiment at the LHC"
Presented by Felix Kling, Arizona State University
Wednesday, November 28, 2018, 2 pm
Small Seminar Room, Bldg. 510New physics has traditionally been expected in the high-pT region at high-energy collider experiments. If new particles are light and weakly-coupled, however, this focus may be completely misguided: light particles are typically highly concentrated within a few mrad of the beam line, allowing sensitive searches with small detectors, and even extremely weakly-coupled particles may be produced in large numbers there. We have propose a new experiment, ForwArd Search ExpeRiment, or FASER, which will be placed downstream of the ATLAS interaction point in the unused service tunnel TI12 and operated concurrently there. FASER will complement the LHC's existing physics program and extend its discovery potential to a host of new particles, such as dark photons and axion-like particles. In this talk, I will describe FASER's location and discovery potential, the detector's layout and components, as well as the experiment's timeline.
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Physics Colloquium
"Studying Quantum Matter on Near-Term Quantum Computers"
Presented by Brian Swingle, University of Maryland and Institute of Advanced Study
Tuesday, November 27, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Rob Pisarski
From the point of view of fundamental physics, one of the greatest promises of quantum information science is a new set of quantum computational tools for addressing previously intractable problems. However, at present we find ourselves in an age of embodied quantum information, where the substrate carrying the information cannot yet be abstracted away and effects of noise cannot be neglected. Nevertheless, I will argue that such noisy, intermediate size quantum devices may be useful for addressing open problems in quantum many-body physics, and potentially quantum field theory. Using two case studies, I will show how quantum information is informing our understanding of quantum matter and how near-term quantum computers might realistically help.
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Nuclear Theory / RIKEN
"Casimir effect in Yang-Mills theory"
Presented by Dimitra Karabali, Lehman College CUNY
Friday, November 16, 2018, 2 pm
CFNS Seminar Room 2-38Hosted by: Niklas Mueller
We consider the Casimir effect in a gauge-invariant Hamiltonian formulation of nonabelian gauge theories in $(2+1)$ dimensions. We compare our analytical results with recent lattice simulations.
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RIKEN Lunch Seminar
"Exclusive $\rho$ meson production in $eA$ collisions: collinear factorization and the CGC"
Presented by Renaud Boussarie, BNL
Thursday, November 15, 2018, 12 pm
Building 510, Room 2-160Hosted by: Yuta Kikuchi
We will focus on the theoretical description of exclusive ρ meson production in eA collisions, using a hybrid factorization scheme which involves Balitsky's shockwave description of the Color Glass Condensate in the t channel, and Distribution Amplitudes (DAs) in the s channel. We will first give a quick introduction to the shockwave framework and to collinear factorization up to twist 3 for DAs, then we will apply these framweworks to the production of a longitudinal meson at NLO accuracy, and to the production of a transverse meson at twist 3 accuracy. We will insist on the experimental applications, and on several theoretical questions raised by our results: the dilute BFKL limit at NLO for diffraction, and collinear factorization breaking at twist 3.
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Environmental & Climate Sciences Department Seminar
"Global models for atmospheric new particle formation from the CERN CLOUD experiment"
Presented by Hamish Gordon, Leeds
Thursday, November 15, 2018, 11 am
Conference Room Bldg 815EHosted by: Laura Fierce
In this seminar I will introduce the CERN CLOUD chamber experiment studying atmospheric new particle formation. I will then focus on work we have done to parameterize new particle formation and growth rates for atmospheric models. I will discuss the implementation of the parameterizations into the models, and the implications of the results from these models for estimated cloud condensation nuclei concentrations and indirect aerosol radiative forcing. The uncertainties in modelling new particle formation remain large, and I will outline how we are moving forward to try to reduce them.
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HET Seminar
"Parton Distribution Functions in Lattice QCD"
Presented by Konstantinos Orginos, College of William and Mary
Wednesday, November 14, 2018, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Aaron Meyer
Computing the x-dependence of parton distribution functions (PDFs) from first principles had been a challenge for many years. Recent theoretical developments have paved the way to perform this computations for the first time using lattice QCD. In this talk I am reviewing these developments. In particular, I will introduce the concepts of quasi-PDFs and pseudo PDFs and discuss their properties. Finally, I will present results from recent calculations and discuss the prospects for the future.
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Physics Colloquium
"From nuts to soup: Recent advances in QCD in the Regge limit and the approach to thermalization in heavy-ion collisions"
Presented by Raju Venugopalan, BNL
Tuesday, November 13, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Rob Pisarski
Twenty five years to date, Larry McLerran and the speaker proposed that the Regge limit of QCD could be described by a many-body classical effective field theory now known as the Color Glass Condensate (CGC). Our radical conjecture was prompted by the phenomenon of gluon saturation, whereby many-body gluodynamics leads to the emergence of a semi-hard scale that screens color in the infrared. In the first part of this talk, we will review developments since in the CGC effective theory, and emphasize a paradigm shift in what constitutes fundamental degrees of freedom in the Regge limit. We shall also outline a color memory effect in the CGC which bears an exact analogy to the gravitational memory effect that could be discovered by LIGO in the near future. This correspondence in turn prompts one to speculate that asymptotic so-called BMS-like symmetries of gravity may also apply in QCD's Regge limit, leading to novel insight into how pions form "soft hair" on glue. In the second part of the talk, we discuss how the CGC provides an ab initio picture of thermalization and hydrodynamics in ultrarelativistic heavy-ion collisions. We focus on the discovery of a pre-thermal turbulent attractor, its topological properties, and a remarkable universality between this attractor and cold atomic gases prepared with the same boundary conditions.
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Nuclear Theory / RIKEN Seminar
"Towards laboratory detection of superfluid phases of QCD"
Presented by Ajit Srivastava, Institute of Physics, Bhubaneswar
Friday, November 9, 2018, 2 pm
CFNS Seminar Room 2-38Hosted by: Niklas Mueller
Exotic phases of QCD exhibiting strong correlations exist at very high baryon density and relatively low temperatures. Examples of such phases range from nucleon superfluid phases expected to occur in the interior of neutron stars, to possible color superconducting phases, which may occur in the core of a neutron stars. Some of these phases may also occur in relativistic heavy ion collisions in the high baryon density regime, e.g. at RHIC (BES), FAIR, and NICA. We discuss the possibilities of detecting them in heavy ion collisions focusing on the universal aspects of associated phase transitions.
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Particle Physics Seminar
"Managing scientific data at the exascale with Rucio"
Presented by Martin Barisits, CERN
Thursday, November 8, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Paul Laycock, Eric Lancon
Rucio is an open source software framework that provides scientific collaborations the functionality to organise, manage, and access their volumes of data. The data can be spread across heterogeneous data centres at widely distributed locations. Rucio has been originally developed to meet the requirements of the high-energy physics experiment ATLAS, and is continuously extended to support the LHC upgrades and more diverse scientific communities. Next to ATLAS, the Xenon1t dark matter search and AMS cosmic ray experiment are also using Rucio in production. The CMS experiment will deploy Rucio by 2019 and operate at a similar scale as ATLAS. Additionally several other experiments such as Belle-2 (B mesons), SKA (radio astronomy), LIGO (gravitational waves), DUNE and IceCube (both neutrino) are currently evaluating Rucio for adoption. This talk will discuss the exascale challenges these scientific experiments face and how Rucio will help to address them. Specifically the possibilities for uncomplicated deployment, easy integration in existing data workflows and the benefit of using the automated services provided by Rucio, will be shown. Also the transition of Rucio from a single-experiment system to an open community project, developed by scientists from multiple experiments, will be presented as well.
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Condensed-Matter Physics & Materials Science Seminar
"Dirac fermions and critical phenomena: exponents and emergent symmetries"
Presented by Michael Scherer, University of Cologne, Germany
Thursday, November 8, 2018, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Laura Classen
Dirac fermions appear as quasi-particle excitations in various condensed-matter systems for example in graphene or as surface states of topological insulators. Close to a quantum phase transition they exhibit a series of exotic properties, e.g., emergent symmetries, fluctuation-induced critical points, the appearance of two length scales and a hierarchy of mass gaps. I discuss mechanisms that are behind these phenomena from a quantum field-theoretical point of view. Further, I present a four-loop renormalization group study for the determination of the Dirac fermions' critical behavior and compare to the predictions of complementary approaches such as quantum Monte Carlo and the conformal bootstrap. Finally, I will also comment on the possibility to test duality conjectures with these calculations.
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NSLS-II Friday Lunchtime Seminar
"Materials Tribology: An Application-Driven Field with Rich Opportunities for Fundamental Studies of Surface Chemistry, Physics, Structure"
Presented by Brandon A. Krick, Department of Mechanical Engineering and Mechanics, Lehigh University
Friday, November 2, 2018, 12 pm
NSLS-II Bldg. 743 Rm 156Hosted by: Ignace Jarrige
The significant economic (~3-6% of developed countries GDP) and environmental (several percent of our annual energy consumption) impacts of friction and wear make tribology is an important, application-driven field. However, there is an opportunity and need for inherently fundamental studies on surface chemistry, physics and structure to elucidate fundamental mechanisms for friction and wear. The non-equilibrium and transient nature of shear-induced changes caused by contacting surfaces in relative motion requires both in situ and ex situ advanced characterization techniques; many of these only available at the light source at Brookhaven. A brief overview of shear-induced (sliding friction/wear) alterations of surfaces will be presented for material systems including: - environmental and tribochemistry molybdenum disulphide based coatings for space applications - shear-induced band bending in GaN - mechanochemistry of polymer nanocomposites
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Particle Physics Seminar
"Search of the rare decay of KL→π0νν at J-PARC"
Presented by Yu-Chen, Tung
Thursday, November 1, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
J-PARC KOTO is a dedicated experiment to search for the rare KL→π0νν decay. This decay is special not only because of its direct CP violating process, but also its theoretical cleanness. In the standard model, the branching ratio of KL→π0νν is calculated to be 3×10-11 with only a few percent uncertainty, which provides a clean base to explore new physics through finding deviations from the standard model. In the recently released results of data collected in 2015, the sensitivity of search was improved by an order of magnitude from the previous result and no event was observed in the signal region, with the prediction of 0.4 background event. In this talk, I will report the analysis and DAQ plan toward the sensitivity of O(-11).
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HET Seminar
"Unveiling New Physics Through Angular Distributions at the LHC"
Presented by Rodolfo Capdevilla, Notre Dame
Wednesday, October 31, 2018, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Gopolang Mohlabeng
Angular distributions are commonly used in high precision measurements at colliders. In this talk, we will use the Collins-Soper angular distribution with two goals; to identify the quantum numbers of the mediators in a simplified dark matter model, and to enhance the signal to background ratio of resonance searches in W gamma production at the LHC with the use of the so called Radiation Amplitude Zero.
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Physics Colloquium
"Cosmic Chandlery with Thermonuclear Supernovae"
Presented by Alan Calder, Stony Brook University
Tuesday, October 30, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Rob Pisarski
Thermonuclear (Type Ia) supernovae are bright stellar explosions distinguished by light curves that can be calibrated to allow for their use as "standard candles" for measuring cosmological distances. Our research investigates how properties of the host galaxy such as composition and age influence properties of the progenitor system, which in turn influence the thermonuclear burning during an event and thus its brightness. I will present the results from ensembles of simulations addressing the influence of age and composition on the brightness of an event. These results show that the outcome depends sensitively on the nuclear burning, particularly weak interactions. Thus precise measurement of the largest possible scales of the Universe requires accurately capturing physics at some of the smallest scales.
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Particle Physics Seminar
"Preparing Physics Software for the Future - the HEP Software Community"
Presented by Benedikt Hegner, BNL
Thursday, October 25, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the High Luminosity LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, the High Energy Physics community created a white paper (arXiv:1712.06982) to describe and define the R&D activities required to prepare for this software upgrade. This presentation describes the expected software and computing challenges and the already taken steps to tackle them
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C-AD Accelerator Physics Seminar
"HL-LHC Crab Cavities and Recent Beam Tests in the SPS Machine"
Presented by Dr. Rama Calaga, CERN
Wednesday, October 24, 2018, 4 pm
Bldg. 911B, Second Floor, Large Conf. Rm., Rm. A2The design, development and challenges of the fabrication of the DQW crab cavity cryomodule is outlined. The successful installation and beam tests with protons in the SPS machine are presented along lessons learned and future plans for the HL-LHC series manufacturing.
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Nuclear Theory/RIKEN Seminar
"Studying out-of-equilibrium Quark-Gluon Plasma with QCD kinetic"
Presented by Aleksas Mazeliauskas, University of Heidelberg
Friday, October 19, 2018, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Niklas Mueller
In relativistic heavy nucleus collisions an ultra-dense, high-temperature state of nuclear matter is created with de-confined quarks and gluons. Understanding how the non-equilibrium Quark-Gluon Plasma thermalizes is important in connecting the initial state physics with the emergent hydrodynamic behavior of the QGP at later times. In this talk, I will use weakly coupled QCD kinetic theory with quark and gluon degrees of freedom to study the QGP evolution in the far-from-equilibrium regime, where it exhibits universal scaling, and its approach to thermal and chemical equilibrium.
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Particle Physics Seminar
"Stronger together: combining searches for new heavy resonances"
Presented by Viviana Cavaliere, Brookhaven National Lab
Thursday, October 18, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
Many theories beyond the Standard Model predict new s-channel resonances decaying into two bosons (WW,ZZ,WZ,WH,ZH) and possibly leptons (ll, lv). This talk will summarize the recent ATLAS combination of heavy resonances searches which places stringent constraints on the couplings to boson, quarks and leptons taking advantage of the statistical combination of searches in different channels. Prospect for future resonances searches at HL-LHC and HE-LHC will be discussed as well.
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HET Seminar
"Flavor Physics in Lattice QCD as a Window into BSM Physics: |Vcb| and the B -> D* l nu Semileptonic Decay"
Presented by Alejandro Vaquero, University of Utah
Wednesday, October 17, 2018, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Aaron Meyer
Flavor physics provides a rich variety of phenomena that can be used to probe the SM without requiring the high energies present only in the largest particle accelerators. Among the quantities that could be employed to perform precision test of the SM, the CKM matrix elements takes up a prominent place. This lecture deals with the |V_{cb}| CKM matrix element, whose determinations through inclusive and exclusive decays currently display a 2\sigma discrepancy, and show how lattice QCD methods can reduce the uncertainty in the theoretical estimates and rule out (or not) the existence of unknown physics at play.
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Center for Functional Nanomaterials Seminar
"Probing nanostructured materials atom by atom: An ultra-high resolution aberration-corrected electron microscopy study"
Presented by Dr. Nasim Alem, Penn State University
Wednesday, October 17, 2018, 10 am
CFN, Bldg 735, Conference Room B, 2nd FloorHosted by: Chuck Black
Defects can have a profound effect on the macroscale physical, chemical, and electronic properties of nanostructures. They can lead to structural distortions, introduce extra states in the band gap and give rise to excess potential locally at buried interfaces. While defects and interfaces have been a well-studied subject for decades, little is known about their local atomic and chemical structure, sub-Angstrom structural distortions within their vicinity, and their stability and transition dynamics under extreme conditions. Using ultra-highresolution aberration-corrected S/TEM imaging and spectroscopy, this talk will discuss our recent efforts on the determination of the defect chemistry and sub-Angstrom relaxation effects in nanostructures around dopants, grain boundaries, domain walls, and interfaces in the family of 2D crystals, complex oxides, and diamond carbon nanothreads. In the family of 2D crystal transition metal dichalcogenides (TMDs) alloys, we show how the formation of chemically ordered states and vacancy/dopant coupling leads to unusual relaxation effects around dopant-vacancy complexes. In addition, we explore stability and transition dynamics of defects leading to grain boundary migration in monolayer TMDs under electron beam irradiation. This talk also presents how ferroelectric polarization emerges at the atomic level across the domain walls in single phase and hybrid complex oxide systems and the impact of this emergence on the macroscale properties. Finally, we uncover the atomic and chemical structure of the carbon nanothreads using low dose high resolution electron microscopy. Bio: Nasim Alem is an assistant professor in the Materials Science and Engineering department at the Penn State University. Nasim received her B.S. degree in Metallurgical Engineering from Sharif University of Technology, Tehran, Iran and her M.S. degree in Materials Science and Engineering from Worcester Polytechnic Institute. She received her PhD from the Ma
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Nuclear Physics Seminar
"Energy dependence of jet quenching signatures in heavy-ion collisions"
Presented by James Brandenburg
Tuesday, October 16, 2018, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
High-pT partons traveling through the quark-gluon plasma (QGP) lose energy due to strong interactions. This effect, called jet-quenching, is attributed to collisional and radiative energy losses as high-pT partons travel through and interact with the dense medium. Over the years jet-quenching has become well established in high-energy heavy-ion collisions. In high-energy A+A collisions, the observation of jet-quenching is considered to be clear evidence of QGP formation. The Beam Energy Scan program at RHIC provided a unique opportunity to study the QCD phase diagram and to search for the turn off of key QGP signatures, such as jet-quenching, at sufficiently low collision energies. The collision energy dependence of jet-quenching effects, quantified through the nuclear modification factor (Rcp) of charged and identified hadrons will be discussed. The limitations of Rcp as an observable will be discussed and compared with a more differential technique for quantifying jet-quenching. Finally, the outlook for improved jet-quenching measurements in the second phase of the RHIC Beam Energy Scan will be presented.
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Condensed-Matter Physics & Materials Science Seminar
"In-situ Investigation of Crystallization of a Metallic Glass by Bragg Coherent X-ray Diffraction"
Presented by Bo Chen, Tongji University, China
Monday, October 15, 2018, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson
The crystallization behaviour of metallic glass (MG) has long been investigated ever since the discovery of these important functional materials [1]. Compared with crystalline and amorphous extremes, mate-rials containing crystalline precipitates within an otherwise amorphous MG or partially crystallized ma-terials have distinct properties that could be a way of tuning the materials' characteristics. Several methods including powder X-ray diffraction (XRD), transmission electron microscope (TEM) and se-lected area electron diffraction (SAED) are usually combined to characterize the degree of crystalline structure in amorphous materials. Until now, these methods, however, have failed to show the crystal-lization of individual crystal grains in three dimensions. In this work, the in-situ Bragg coherent X-ray diffraction imaging (BCDI) [2, 3] reveals the grain growth and the strain variation of individual crystals up to the sizes of a few hundred nanometers from the pure Fe-based MG powder during heating. We have found that there is preferential growth along one direction during the crystal formation; there is fractal structure around the developing crystal surface; there is also strain relaxation within the growing crystals while cooling. The work supports a two-step crystallization model for the Fe-based MG during heating. This could help to pave the way for designing partially crystalline materials with their at-tendant soft magnetic, anti-corrosive and mechanical properties. References [1] D. H. Kim, W. T. Kim, E. S. Park, N. Mattern, and J. Eckert, Prog. Mater. Sci. 2013, 58, 1103. [2] M. A. Pfeifer, G. J. Williams, I. A. Vartanyants, R. Harder and I. K. Robinson, Nature 2006, 442, 63. [3] I. K. Robinson and R. Harder, Nat. Mater. 2009, 8, 291.
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Nuclear Theory/RBRC Seminar
"Anyonic particle-vortex statistics and the nature of dense quark matte"
Presented by Srimoyee Sen, University of Arizona
Friday, October 12, 2018, 2 pm
Building 510, Room 2-38Hosted by: Andrey Tarasov
We show that Z_3-valued particle-vortex braiding phases are present in high density quark matter. Certain mesonic and baryonic excitations, in the presence of a superfluid vortex, have orbital angular momentum quantized in units of 1/3. Such non-local topological features can distinguish phases whose realizations of global symmetries, as probed by local order parameters, are identical. If Z_3 braiding phases and angular momentum fractionalization are absent in lower density hadronic matter, as is widely expected, then the quark matter and hadronic matter regimes of dense QCD must be separated by at least one phase transition.
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NSLS-II Colloquium Series
"Biophysical Studies of an RNA Virus particle and its Maturation: Insights into an Elegantly Programmed Nano-machine"
Presented by John E. (Jack) Johnson, Department of Integrative Structural and Computational Biology, The Scripps Research Institute
Thursday, October 11, 2018, 4 pm
Large Seminar Room, Bldg. 510Hosted by: John Hill
Nudaurelia Capensis ? Virus (N?V) is a eukaryotic, quasi-equivalent, RNA virus, with a T=4 surface lattice, where maturation is dramatic (a change in particle size of 100Å) and is novel in that it can be investigated in vitro. Here we use X-ray crystallography, biochemistry, Small Angle X-ray Scattering, and electron cryo-microscopy and image reconstruction (CryoEM), to characterize maturation intermediates, an associated auto-catalytic cleavage, the kinetics of morphological change and to demonstrate that regions of N?V subunit folding are maturation-dependent and occur at rates determined by their quasi-equivalent position in the capsid. Matsui, T., Lander, G. C., Khayat, R., and Johnson, J. E. 2010. Subunits fold at position-dependent rates during maturation of a eukaryotic RNA virus. Proc Natl Acad Sci U S A 107:14111-5. Veesler, D., and Johnson, J.E. 2012. Virus Maturation. Annual review of biophysics 41:473-496. Doerschuk, P. C., Gong, Y., Xu, N., Domitrovic, T., and Johnson, J. E. 2016. Virus particle dynamics derived from CryoEM studies. Curr Opin Virol 18:57-63.
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Particle Physics Seminar
"Higgs to beauty quarks"
Presented by Caterina Vernieri, SLAC
Thursday, October 11, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The Higgs boson discovery at the LHC marked a historic milestone in the study of fundamental particles and their interactions. Over the last six years, we have begun measuring its properties, which are essential to build a deep understanding of the Higgs sector of the Standard Model and to potentially uncover new phenomena. The Higgs' favored decay mode to beauty (b) quarks (~60%) had so far remained elusive because of the overwhelming background of b-quark production due to strong interactions. Observing the Higgs decay to b-quarks was one of the critical missing pieces of our knowledge of the Higgs sector. Measuring this decay is a fundamental step to confirm the mass generation for fermions and may also provide hints of physics beyond the Standard Model. The CMS observation of the decay of the SM Higgs boson into a pair of b-quarks exploiting an exclusive production mode (VH) is yet another major milestone. This experimental achievement at the LHC, considered nearly impossible in the past, makes use of several advanced machine learning techniques to identify the b-quark distinctive signature, improve the Higgs boson mass resolution, and discriminate the Higgs boson signal from background processes.
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NSLS-II Friday Seminar
"Highly Active and Stable Carbon Nanosheets Supported Iron Oxide for Fischer-Tropsch to Olefins Synthesis"
Presented by Congjun Wang, National Energy Technology Laboratory, Pittsburgh, PA
Friday, October 5, 2018, 12 pm
NSLS-II Bldg. 743 Rm 156Hosted by: Ignace Jarrige
Light olefins production utilizes the energy intensive process of steam cracking. Fischer-Tropsch to olefins (FTO) synthesis potentially offers a more sustainable alternative. Here we show a promising FTO catalyst comprised of iron oxide nanoparticles supported on carbon nanosheets (CNS) fabricated from the carbonization of potassium citrate, which incorporates well dispersed K-promoter throughout the CNS support. This catalyst exhibits, to the best of our knowledge, the highest iron time yield of 1790–1990 μmolCO/gFe•s reported in the literature, 41% light olefins selectivity, and over 100 hours stable activity, making it one of the best performing FTO catalysts. Detailed characterization, including synchrotron X-ray spectroscopy, illustrates that the CNS support facilitates iron oxide reduction to metallic iron, leading to efficient transformation to the active iron carbide phase during FTO reaction. Since K is a commonly used promoter, our K-promoted CNS support potentially has broad utility beyond the FTO reactions demonstrated in the current study.
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Particle Physics Seminar
"SB/BNL Joint Cosmo seminar: Weighing Galaxy Clusters with Weak Lensing in Hyper Suprime-Cam Survey"
Presented by Dr. Elinor Medezinski, Princeton University
Thursday, October 4, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chi-Ting Chang
The most fundamental question in observational cosmology today is what is the nature of dark energy and dark matter. Clusters of galaxies serve as beacons to the growth of structure over cosmic scales, making them a sensitive cosmological tool. However, accurately measuring their masses has been notoriously difficult. Weak lensing provides the best direct probe of the cluster mass, both the baryonic and dark components, but it requires high-quality wide-field imaging and careful control of systematics. With its unprecedentedly deep and exquisite seeing, the Subaru Hyper Suprime-Cam (HSC) survey is an ongoing campaign to observe 1,400 square degrees to r~26, providing the closest precursor to LSST. In this talk, I will present our new field-leading results from the first HSC data release of ~150 square degrees that encompass thousands of clusters. Harnessing our new HSC survey, I measure benchmark weak lensing cluster masses with improved methodology, and reconcile previous tension on cosmological parameters between the SZ and CMB within the Planck survey. In the next decade, LSST and WFIRST will discover hundreds of thousands of galaxy clusters, peering deep to the epoch of formation. I will describe these surveys and the multifold breakthrough science we will achieve in the new era of astronomy.
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Special Particle Physics Seminar
"Latest XENON1T results"
Presented by Qing Lin, Columbia University
Thursday, October 4, 2018, 1 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
Understanding the properties of dark matter particle is a fundamental problem in particle physics and cosmology. The search of dark matter particle scattering off nuclei target using ultra-low background detector is one of the most promising technology to decipher the nature of dark matter. The XENON1T experiment, which is a dual phase detector with ~2.0 tons of xenon running at the Gran Sasso Laboratory in Italy, is designed to lead the field of dark matter direct detection. Since November 2016, the XENON1T detector is continuously taking data, with a background rate of more than one order of magnitude lower than any current generation dark matter search experiment. In this talk, I will present the latest results from XENON1T. Details about the XENON1T detector as well as the data analysis techniques will also be covered.
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Nuclear Physics Seminar
"Exploring the Phase Diagram with Succeptibility Scaling Functions: Epic Voyage or Just Another Bad Trip"
Presented by Roy A Lacey, Stony Brook University
Tuesday, October 2, 2018, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jiangyong Jia
A major goal of the ongoing experimental programs at RHIC is to chart the QCD phase diagram.Pinpointing the location of the first order phase boundary which terminates at a critical end point (CEP), in the temperature versus baryon chemical potential (T,µB) plane of this phase diagram, is key to this mapping. Finite-Size-Finite-Time succeptibility scaling functions can give crucial insight on these essential landmarks of the phase diagram. I will discuss recent attempts to extract and use such scaling functions to pin down the location of the CEP, as well as the associated critical exponents required to identify its universality class.
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Particle Physics Seminar
"(Somewhat) New ideas in ultralight DM searches:"
Presented by Babette Döbrich, CERN
Monday, October 1, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The search for ultra-light Dark Matter particles complements the search for more ``classical'' Dark Matter candidates at the GeV scale in an important fashion. I will review the motivation of the QCD axion, highlighting ongoing established techniques and set-ups and explain in detail a novel technique based on microwave filters (RADES), ongoing at CERN. Finally I will present results of one of the possibly cheapest experiments for ultralight Dark Photon Dark Matter (FUNK) achieving competitive results.
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Nuclear Theory/RIKEN Seminar
"Neutrinoless double beta decay in effective field theory"
Presented by Jordy De Vries, UMass Amherst
Friday, September 28, 2018, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Chun Shen
Next-generation neutrinoless double-beta decay experiments aim to discover lepton-number violation in order to shed light on the nature of neutrino masses. A non-zero signal would have profound implications by demonstrating the existence of elementary Majorana particles and possibly pointing towards a solution of matter-antimatter asymmetry in the universe. However, the interpretation of the experimental signal (or lack thereof) requires care. First of all, a single nonzero measurement would indicate lepton-number violation but will not identify the underlying source. Second, complicated hadronic and nuclear input is required to connect the experimental data to a fundamental description of lepton-number violation. In this talk, I will use effective field theories to connect neutrinoless double-beta decay measurements to the fundamental lepton-number-violating source.
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Particle Physics Seminar
"Measurements of the branching fraction and time-dependent CP asymmetries for B0 -> J/psi pi0 decays"
Presented by Bilas Pal, BNL
Thursday, September 27, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: David Jaffe
Measurements of the time-dependent CP asymmetries and branching fraction of B0 -> J/psi pi0 will be discussed. The CP asymmetry parameters for the decay B0 -> J/psi pi0 have previously been measured by BaBar and Belle experiments, but the results of mixing induced CP asymmetry (S) were not in good agreement with each other. Furthermore, the BaBar result lies outside the physically allowed region. Previous Belle measurements were based on 535M BB-bar pairs. We updated the measurements using the final Belle data set of 772M BB-bar pairs.
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Condensed-Matter Physics & Materials Science Seminar
"Universality and quantum criticality of the one-dimensional spinor Bose gas"
Thursday, September 27, 2018, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201Hosted by: Igor Zaliznyak
We investigate the universal thermodynamics of the two-component one-dimensional Bose gas with contact interactions in the vicinity of the quantum critical point separating the vacuum and the ferromagnetic liquid regime. We find that the quantum critical region belongs to the universality class of the spin-degenerate impenetrable particle gas which, surprisingly, is very different from the single-component case and identify its boundaries with the peaks of the specific heat. In addition, we show that the compressibility Wilson ratio, which quantifies the relative strength of thermal and quantum fluctuations, serves as a good discriminator of the quantum regimes near the quantum crit- ical point. Remarkably, in the Tonks-Girardeau regime the universal contact develops a pronounced minimum, reflected in a counterintuitive narrowing of the momentum distribution as we increase the temperature. This momentum reconstruction, also present at low and intermediate momenta, signals the transition from the ferromagnetic to the spin-incoherent Luttinger liquid phase and can be detected in current experiments with ultracold atomic gases in optical lattices.
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Sustainable Energy Technologies Department
"Advances in Ultra-High Energy Resolution STEM-EELS"
Presented by Tracy C. Lovejoy, Nion R&D
Wednesday, September 26, 2018, 2 pm
Bldg. 734, Room 201Hosted by: Feng Wang
The capabilities of scanning transmission electron microscopes (STEMs) have advanced very significantly in the last two decades. The first major advance was the successful implementation of electron-optical aberration correction, which allowed the STEMs to reach direct sub-angstrom resolution in 2002 [1]. This improvement made the imaging and spectroscopy of single atoms straightforward. A very recent major development has been the improvement of energy resolution of EELS due to the introduction of a new generation of monochromators and ultra-stable electron spectrometers. The Ultra-High Energy Resolution Monochromated EELS-STEM (U-HERMES™) system developed by Nion combines a dispersing-undispersing ground-potential monochromator [2], a bright cold-field-emission gun, an advanced aberration corrector, and a new EEL spectrometer. The latest version of the system allows 5 meV energy resolution EELS and has achieved 1.07 Å spatial resolution at the sample at 30kV when monochromating, and it greatly extends the capabilities of vibrational spectroscopy in the EM, introduced 4 years ago [3]. U-HERMES™ has so far been used for: damage-free identification of different bonds including hydrogen bonds in guanine [4]; probing atomic vibrations at surfaces and edges of nano-objects with nm-level spatial resolution [5]; achieving sub-nm spatial resolution in images obtained with dark-field EELS vibrational signals [6]; nanoscale mapping of phonon dispersion curves [7]; nanoscale temperature determination by electron energy gain spectroscopy [8]; identification of different isotopes by vibrational spectroscopy in the EM [9]; vibrational spectroscopy of ice; and vibrational fingerprinting of biological molecules.
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Physics Colloquium
"Unraveling the nucleon's mass and spin structure at an Electron-Ion Collider"
Presented by Yoshitaka Hatta, BNL and Kyoto University
Tuesday, September 25, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Rob Pisarski
The US-based Electron-Ion Collider (EIC) is a future high-luminosity, polarized collider dedicated to the physics of the nucleon/nucleus structure. Among the many physics problems that can be addressed at the EIC, I will focus on the origin of the mass and spin of the nucleon, namely, how they can be understood in terms of quarks' and gluons' degrees of freedom. I will give a review of the mass and spin decompositions in QCD and discuss possible experimental observables.
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Particle Physics Seminar
"Searches for decays of a Higgs boson into pairs of light (pseudo)scalars with the ATLAS detector"
Presented by Ljiljana Morvaj
Tuesday, September 25, 2018, 10:30 am
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The branching ratio of the Standard Model (SM) Higgs boson to non-SM or "exotic" states is currently constrained to be less than 34% at 95% confidence level. This opens possibility to search for new particles in the decays of the Higgs boson. Such searches could provide a unique access to hidden-sector states that are singlets under the SM gauge transformations. A search for decays of the Higgs boson to a pair of new spin–0 particles, H → aa, where the a–bosons decay to a b-quark pair and a muon pair, is presented in this seminar. The analysis uses 36.1 fb−1 of proton-proton collisions data with √s = 13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No deviation from the Standard Model prediction is observed and limits on Br(H → aa → bbμμ) are set in the a–boson mass range of 20–60 GeV. Searches in other final states, such as four b-quarks (H → aa → 4b) and two jets and two photons (H → aa → ggγγ), are also discussed.
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Nuclear Theory/RIKEN Seminar
"Status of Pythia 8 for an Electron-Ion Collider"
Presented by Ilkka Helenius, University of Tubingen
Friday, September 21, 2018, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Andrey Tarasov
Pythia 8 is a general-purpose Monte-Carlo event generator widely used to simulate high-energy proton-proton collisions at the LHC. Recently it has been extended to handle also other collision systems involving lepton and heavy-ion beams. In this seminar I will review the current Pythia 8 capabilities in processes relevant to an Electron-Ion Collider (EIC) and discuss about the projected future improvements. The relevant processes can be divided into two regions based on the virtuality of the intermediate photon: deeply inelastic scattering (DIS) at high virtualities and photoproduction at low virtualities. I will begin with an introduction of the event generation steps in Pythia 8 and then briefly discuss how the DIS processes can be simulated. Then I present our photoproduction framework and compare the results to the HERA data for charged-hadron and dijet production in lepton-proton collisions. In particular I discuss about the role of multiparton interactions in photon-proton interactions with resolved photons and how these can be constrained with the existing HERA data. Then I discuss how the same framework can be applied to ultra-peripheral heavy-ion collisions at the LHC where one can study high-energy photon-nucleus interactions in a kinematic region comparable to EIC. Finally I will show our first predictions for dijet production in these events and quantify the contribution of diffractive events according to the hard diffractionmodel that has been recently implemented into Pythia 8.
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Particle Physics Seminar
"The Belle II Experiment"
Presented by Bryan Fulsom, PNNL
Thursday, September 20, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: David Jaffe
The first generation of B-Factories, BaBar and Belle, operated over the previous decade and produced many world-leading measurements related to flavor physics. Their discoveries contributed to the awarding of the 2008 Nobel Prize in Physics. The Belle II experiment, now underway at the KEK laboratory in Japan, is a substantial upgrade of both the Belle detector and the KEKB accelerator. It aims to collect 50 times more data than existing B-Factory samples. This will provide unprecedented sensitivity to new physics signatures in the flavor sector. This talk will present the upgrade efforts of the Belle II experiment, results from its recent first e+e- collisions, and the future physics opportunities the experiment will provide.
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Condensed-Matter Physics & Materials Science Seminar
"Multiloop functional renormalization group: Exact flow equations from the self-consistent parquet relations"
Presented by Fabian Kugler, Ludwig-Maximilians-Universitat Munchen, Germany
Thursday, September 20, 2018, 1:30 pm
ISB 734 Conference Room 201Hosted by: Andreas Weichselbaum
The functional renormalization group (fRG) is a versatile, quantum-field-theoretical formulation of the powerful RG idea and has seen a large number of successful applications. The main limitation of this framework is the truncation of the hierarchy of flow equations, where typically effective three-particle interactions are neglected altogether. From another perspective, the parquet formalism consists of self-consistent many-body relations on the one- and two-particle level and allows for the most elaborate diagrammatic resummations. Here, we unify these approaches by deriving multiloop fRG flow equations from the self-consistent parquet relations [1]. On the one hand, this circumvents the reliance on higher-point vertices within fRG and equips the method with quantitative predictive power [2]. On the other hand, it enables solutions of the parquet equations in previously unaccessible regimes. Using the X-ray-edge singularity as an example, we introduce the formalism and illustrate our findings with numerical results [3]. Finally, we discuss applications to the 2D Hubbard model [4] and the combination of multiloop fRG with the dynamical mean-field theory. [1] F. B. Kugler and J. von Delft, arXiv:1807.02898 (2018) [2] F. B. Kugler and J. von Delft, PRB 97, 035162 (2018) [3] F. B. Kugler and J. von Delft, PRL 120, 057403 (2018) [4] A. Tagliavini, C. Hille, F. B. Kugler, S. Andergassen, A. Toschi, and C. Honerkamp, arXiv:1807:02697 (2018)
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Physics Colloquium
"Potential and Issues for Future Accelerators and Ultimate"
Presented by Stephen Brooks, BNL
Tuesday, September 18, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Andrei Nomerotski
Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.
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Special Particle Physics Seminar
"Flavor physics and CP violation - Recent results from combined BaBar+Belle measurements, ongoing work at LHCb, and prospects for the new physics searches at Belle II"
Presented by Markus Roehrken, CERN
Monday, September 17, 2018, 1 pm
Small Seminar Room, Bldg. 510Hosted by: David Jaffe
During the 2000s, the BaBar experiment at SLAC (Stanford/USA) and the Belle experiment at KEK (Tsukuba/Japan) performed a very successful flavor physics program. BaBar and Belle discovered CP violation in the B meson system and put tight experimental constraints on the quark-flavor sector of the Standard Model. The excellent experimental confirmation of the theory predictions by BaBar and Belle led to the Nobel Prize in physics for Makoto Kobayashi and Toshihide Maskawa in 2008. Continuing on these efforts, the new high-luminosity accelerator SuperKEKB and the next-generation B factory experiment Belle II recently started operation at KEK in Japan. SuperKEKB is designed to operate at an instantaneous luminosity of 8x10^35/cm^2/s, which is a factor 40 higher than the world record achieved by its predecessor KEKB. The upgraded Belle II detector will collect data samples about two orders of magnitudes larger than those of the BaBar and Belle experiments. In this talk, we introduce to flavor physics and CP violation. We will present recent results of a combined analysis campaign, which for the first time makes simultaneous use of the large final data samples of BaBar and Belle in single physics analyses. The approach provides access to an integrated luminosity of about 1.1 inverse attobarn, and thus allows to perform early Belle II-like measurements. In addition, ongoing work of the speaker at LHCb is reported. At the end of the talk, the prospects for the new physics searches in heavy flavor decays governed by quantum-loop effects at Belle II are briefly discussed.
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Particle Physics Seminar
"Probing the Higgs Yukawa couplings at the LHC"
Presented by Konstantinos Nikolopoulos
Thursday, September 13, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Alessandro Tricoli
The Higgs boson observation by ATLAS and CMS Collaborations at the CERN Large Hadron Collider has completed the Standard Model; the culmination of a century of discoveries. Despite the overwhelming success of the Standard Model to-date, the origin of fermion masses through Yukawa couplings to the Higgs doublet is loosely constrained experimentally and offers opportunities for BSM physics contributions. The status of the determination of the Higgs boson Yukawa couplings at the LHC will be presented and the prospects for the future will be discussed.
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Joint BNL/RIKEN HET Seminar
"Higgs pair production via gluon fusion at NLO QCD"
Presented by Julien Baglio, Tuebingen U.
Wednesday, September 12, 2018, 2 pm
Small Seminar Room, Bldg. 510Hosted by: Sally Dawson
Since the discovery of a Higgs boson in 2012 at CERN, accessing its properties is one of the main goals of the Large Hadron Collider (LHC) experimental collaborations. The triple Higgs coupling in particular is a primary target as it would be a direct probe of the shape of the scalar potential at the origin of the electroweak-symmetry-breaking mechanism, and is directly accessed via the production of a pair of Higgs bosons. In this view, it is of utmost importance to reach high precision in the theoretical prediction of Higgs boson pair production cross section at the LHC. I will present in this talk the calculation of the 2-loop QCD corrections to the Higgs-pair-production cross section via gluon fusion, that is the main production mechanism, including the top-quark mass effects in the loops. It will be shown that they can be significant in the Higgs-pair-mass differential distributions.
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Nuclear Theory/RBRC Seminar
"Temperature, Mass, Flavor: Emerging Phase Structure of SU(3) Gauge Theories with Fundamental Quarks"
Presented by Ivan Horvath, University of Kentucky
Friday, September 7, 2018, 2 pm
Small Seminar Room, Bldg. 510Hosted by: Rob Pisarski
Recently we have outlined the general phase structure of the above relevant theory set, inferred from probing the glue by external Dirac probes. Its novelty and simplicity stems from the conclusion that changes in temperature, mass and number of flavors lead to analogous dynamical effects. In this talk I will review that picture, and introduce an important refinement of it that is currently emerging in the thermal corner of the phase diagram.
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Condensed-Matter Physics & Materials Science Seminar
"Pair-breaking quantum phase transition in superconducting nanowires"
Presented by Andrey Rogachev, University of Utah
Friday, September 7, 2018, 11 am
ISB Bldg. 734 Conference Room 201 (upstairs)Hosted by: Ivan Bozovic
Quantum phase transitions (QPT) between distinct ground states of matter are widespread phenomena, yet there are only a few experimentally accessible systems where the microscopic mechanism of the transition can be tested and understood. In this talk we will report on discovery that a magnetic-field driven quantum phase transition in MoGe superconducting nanowires can be fully explained by the critical theory of pair-breaking transitions characterized by a correlation length exponent v≈1 and dynamic critical exponent z≈ 2. We find that in the quantum critical regime, the electrical conductivity is in agreement with a theoretically predicted scaling function and, moreover, that the theory quantitatively describes the dependence of conductivity on the critical temperature, field magnitude and orientation, nanowire cross-sectional area, and microscopic parameters of the nanowire material. At the critical field, the conductivity follows a T^(d–2)/z dependence predicted by phenomenological scaling theories and more recently obtained within a holographic framework. Our work uncovers the microscopic processes governing the transition: the pair-breaking effect of the magnetic field on interacting Cooper pairs overdamped by their coupling to electronic degrees of freedom. It also reveals the universal character of continuous quantum phase transitions. In the talk we will also briefly comment on reliability of the finite-size scaling analysis, origin of zero-bias anomaly in wires and implication of our finding for QPT in superconducting films.
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RIKEN/NT & Quantum Computing Seminar
"Quantum Uncertainty and Quantum Computation"
Presented by Ivan Horvath, University of Kentucky
Thursday, September 6, 2018, 12:30 pm
Building 510, Room 2-160Hosted by: Rob Pisarski
I will discuss the uncertainty in quantum mechanics as a property reflecting the "quantity" (measure) on the set of possible probing outcomes. This is in contrast to the commonly used "spectral distance" (metric). An unexpected insight into the nature of quantum uncertainty (and that of measure) is obtained as a result. One of the motivations for considering measure uncertainty is that it is directly relevant for assessing the efficiency of quantum computation.
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Nuclear Physics Seminar
"Neutron production and capture in stellar nucleosynthesis:^{22}Ne(\Alpha,n)^{25}Mg reaction and radiative neutron captures of radioactive nuclei"
Presented by Shuya Ota, Texas A&M University
Tuesday, September 4, 2018, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
Most of elements heavier than Fe in the Universe are produced by a series of neutron capture reaction and ??-decay in stars. The s-process, which occurs under moderate neutron environments (~107-10 neutrons/cm3) such as in He burning of massive stars, is responsible for producing almost half of the heavy elements. Neutrons for the s-process environment is believed to be supplied by two dominant reactions, one of which is 22Ne(?,n)25Mg reaction. This reaction in massive stars is dominated by a few resonance reactions. Nevertheless, there remain large uncertainties about contribution of the reaction to the s-process nucleosynthesis because the reaction cross sections are too small for direct measurements due to Coulomb barrier (E? = 400-900 keV in the lab system). In the first half of this seminar, I will present our experiment to determine these resonance strengths with a cyclotron accelerator at Texas A&M University. The experiment was performed by an indirect approach using 6Li(22Ne,25Mg+n)d ?-transfer reaction, in which resonance properties such as neutron decay branching ratios of produced 26Mg were studied by measuring deuterons, ?-ray, and 26Mg in coincidence using large arrays of Si and Ge, and a magnetic spectrometer. Our results showed neutron production from 22Ne(?,n)25Mg reaction can be about 10 times lower than past measurements. The effect of our measurements on the s-process nucleosynthesis will be discussed. In the second half of this seminar, I will present our experiments to determine neutron capture cross sections of radioactive nuclei using the Surrogate Reaction method [1]. Neutron capture reactions for the s-process involve relatively long-lived nuclei neighboring stability in the nuclear chart. Therefore, the Surrogate Reaction, which creates the same compound nuclei as the neutron capture reaction using a stable beam and target, can be a useful approach. On the other hand, the r- process, which produces the other half
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Special Nuclear Theory/RIKEN Lunch Seminar
"Signal-to-noise issues in non-relativistic quantum matter: from entanglement to thermodynamics"
Presented by Joaquin Drut, University of North Carolina
Thursday, August 30, 2018, 12:30 pm
Building 510, Room 2-160Hosted by: Rob Pisarski
Non-relativistic quantum matter, as realized in ultracold atomic gases, continues to be a remarkably versatile playground for many-body physics. Experimentalists have exquisite control over temperature, density, coupling, and shape of the trapping potential. Additionally, a wide range of properties can be measured: from simple ones like equations of state to more involved ones like the bulk viscosity and entanglement. The latter has received much attention due to its connection to quantum phase transitions, but it has proven extremely difficult to compute: stochastic methods display exponential signal-to-noise issues of a very similar nature as those due to the infamous sign problem affecting finite-density QCD. In this talk, I will present an algorithm that solves the signal-to-noise issue for entanglement, and I will show results for strongly interacting systems in three spatial dimensions that are the first of their kind. I will also present a few recent explorations of the thermodynamics of polarized matter and other cases that usually have a sign problem, using complexified stochastic quantization.
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Nuclear Physics Seminar
"Probe strong magnetic field in QGP with dielectrons from photon-photon interactions"
Presented by Zhangbu Xu, BNL
Tuesday, August 28, 2018, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
We presents first measurements of $e^+e^-$ pair production from light-light scattering in non-central heavy ion collisions. The excess yields peak distinctly at low transverse momentum with sqrt() between 40 to 60 MeV/c. The excess yields can be explained only when the photon-photon interactions are included in model calculations. However, the measured pT^2 distributions are significantly broader than model calculation and are different between Au+Au and U+U. Our measurements provide a possible experimental evidence of the existence of strong electromagnetic field. And I will discuss its possible impact on emerging phenomena in hadronic heavy-ion collisions, such as Chiral Magnetic Effect.
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Condensed-Matter Physics & Materials Science Seminar
"Spinon Confinement and a Longitudinal Mode in One Dimensional Yb2Pt2Pb"
Presented by Bill Gannon, Department of Physics and Astronomy, Texas A&M University
Thursday, August 23, 2018, 1:30 pm
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Alexei Tsvelik
Abstract: The Yb3+ magnetic moments in Yb2Pt2Pb are seemingly classical, since the large spin-orbit coupling of the 4f-electrons and the crystal electric field dictate a J = +/-7/2 Yb ground state doublet. Surprisingly, the fundamental low energy magnetic excitations in Yb2Pt2Pb are spinons on one dimensional chains, shown to be in good agreement with the behavior expected with the XXZ Hamiltonian for nearly isotropic, S = +/-1/2 magnetic moments. We have performed new high resolution neutron scattering measurements to examine the properties of these excitations in a magnetic field. In fields larger than 0.5 T, the chemical potential closes the gap to the spinon dispersion, modifying the quantum continuum through the formation of a spinon Fermi surface. This leads to the formation of spinon bound states along the chains, coupled to a longitudinally polarized interchain mode at energies below the quantum continuum. The ground state doublet nature of the Yb ions ensures that at all fields, transverse excitations are virtually nonexistent, allowing direct measurement of the mode dispersion.
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HET Lunch Discussions
"Lattice QCD Study of Exclusive Channels in the Muon HVP"
Presented by Aaron Meyer, BNL
Friday, August 17, 2018, 12:15 pm
Building 510, Room 2-160Hosted by: Christoph Lehner
The hadronic vacuum polarization is a dominant contribution to the theoretical uncertainty of the muon anomalous magnetic moment. Both the R-ratio and Lattice QCD may be used to compute the HVP contribution from theory, and the theoretical uncertainties for both methods are statistically precise in regions that are complimentary to each other. For lattice QCD, the long-distance region dominates the statistical uncertainty. By explicitly studying exclusive channels of the HVP diagram with lattice QCD, it is possible to reconstruct the long-distance behavior of the correlation function. This has the effect of replacing the statistical uncertainty with a significantly smaller systematic uncertainty. With this long-distance reconstruction, it will be possible to achieve a precision with a lattice-only calculation similar to that of the R-ratio method.
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RIKEN Lunch Seminar
"Universality in Classical and Quantum Chaos"
Presented by Masanori Hanada, YITP
Thursday, August 16, 2018, 12:30 pm
Building 510, Room 2-160Hosted by: Enrico Rinaldi
We study the chaotic nature of classical and quantum systems. In particular, we will study the detail of the Lyapunov growth. We will show the evidence that the spectrum of Lyapunov exponents admits universal description by Random Matrix Theory, and systems dual to black holes exhibit 'strong' universality.
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Condensed-Matter Physics & Materials Science Seminar
"Advances in high energy electron holography"
Presented by Dr. Toshiaki Tanigaki, Hitachi, Japan
Friday, August 10, 2018, 1:30 pm
Conference room in building 480Hosted by: MG Han
Advances in High-Voltage Electron Holography T. Tanigaki Research & Development Group, Hitachi, Ltd. Email: toshiaki.tanigaki.mv@hitachi.com Electron holography can observe electromagnetic field inside materials and devices at high-resolution around atomic scale. The high penetration power of a high energy electron wave is crucial to observing magnetic structures, which exist only in thick samples. It is particularly crucial in three-dimensional (3D) observations, which require a series of sample observations with the sample increasingly tilted so that the projected sample thickness increases with the tilt angle. As an example of this, magnetic vortex cores confined in stacked ferromagnetic (Fe) discs were observed three-dimensionally by using vector-field electron tomography with a 1.0 MV holography electron microscope [1]. To invent new functional materials and devices for establishing a sustainable society, methods for controlling atomic arrangements in small areas such as interfaces have become important [2,3]. Electron holography is a powerful tool for analyzing the origins of functions by observing electromagnetic fields and strains at high resolutions. The advantages of high-voltage electron holography are high resolution and penetration power due to high energy electron waves. The quest for finding the ultimate resolution through continuous improvements on holography electron microscopes led to the development of an aberration corrected 1.2 MV holography electron microscope [4,5] (Figure 1). We describe recent results obtained by using the high-voltage electron holography. Spatial resolution of 1.2 MV holography electron microscope reached 0.043 nm at high-resolutions, when the sample was placed in a high magnetic field of the objective lens [4]. Under the observation conditions, in which the sample was placed in a field-free position for observing a magnetic field, the spatial res
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Special Particle Physics Seminar
"Deep Neural Network Techniques R&D for Data Reconstruction of Liquid Argon TPC Detectors"
Presented by Kazuhiro Terao, SLAC National Accelerator Laboratory
Tuesday, August 7, 2018, 10 am
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
Liquid Argon Time Projection Chambers (LArTPCs) are capable of recording images of charged particle tracks with breathtaking resolution. Such detailed information will allow LArTPCs to perform accurate particle identification and calorimetry, making it the detector of choice for many current and future neutrino experiments. However, analyzing such images can be challenging, requiring the development of many algorithms to identify and assemble features of the events in order to reconstruct neutrino interactions. In the recent years, we have been investigating a new approach using deep neural networks (DNNs), a modern solution to a pattern recognition for image-like data in the field of Computer Vision. A modern DNN can be applied for various types of problems such as data reconstruction tasks including interaction vertex finding, pixel clustering, and particle/topology type identification. We have developed a small inter-experiment collaboration to share generic software tools and algorithms development effort that can be applied to non-LArTPC imaging detectors. In this talk I will discuss the challenges of LArTPC data reconstruction, recent work and future plans for developing a full LArTPC data reconstruction chain using DNNs.
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Special HET Seminar
"A New Frontier in the Search for Dark Matter"
Presented by Gordan Krnjaic, FNAL
Monday, August 6, 2018, 1:30 pm
Small Seminar Room, Bldg. 510Hosted by: Sally Dawson
The gravitational evidence for the existence of dark matter is overwhelming; observations of galactic rotation curves, the CMB power spectrum, and light element abundances independently suggest that over 80% of all matter is "dark" and beyond the scope of the Standard Model. However, its particle nature is currently unknown, so discovering its potential non-gravitational interactions is a major priority in fundamental physics. In this talk, I will survey the landscape of light dark matter theories and and introduce an emerging field of fixed-target experiments that are poised to cover hitherto unexplored dark matter candidates with MeV-GeV masses. These new techniques involve direct dark matter production with proton, electron, and *muon* beams at various facilities including Fermilab, CERN, SLAC, and JLab. Exploring this mass range is essential for fully testing a broad, predictive class of theories in which dark matter abundance arises from dark-visible interactions in thermal equilibrium in the early universe.
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Particle Physics Seminar
"Significant Excess of Electron-Like Events in the MiniBooNE Short-Baseline Neutrino Experiment"
Presented by William Louis, Los Alamos National Lab
Thursday, August 2, 2018, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Chao Zhang
The MiniBooNE experiment at Fermilab observes a total electron-neutrino event excess in both neutrino and antineutrino running modes of 460.5 +- 95.8 events (4.8 sigma) in the energy range from 200-1250 MeV. The MiniBooNE L/E distribution and the allowed region from a two-neutrino oscillation fit to the data are consistent with the L/E distribution and allowed region reported by the LSND experiment. All of the major backgrounds are constrained by in-situ event measurements, so non-oscillation explanations would need to invoke new anomalous background processes. Although the data are fit with a two-neutrino oscillation model, other models may provide better fits to the data. The MiniBooNE event excess will be further studied by the Fermilab short-baseline neutrino (SBN) program.
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Condensed-Matter Physics & Materials Science Seminar
"Imaging Non-equilibrium Dynamics in Two-Dimensional Materials"
Presented by Kenneth Beyerlein, Max Planck Institute for the Structure and Dynamics of Matter, Germany
Wednesday, August 1, 2018, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Ian Robinson
The interfaces in thin film heterostructures dictate the performance of an electronic device. Understanding their behavior upon exposure to light is important for advancing photovoltaics and spintronics. However, producing an atomic image of these dynamics is an under-determined problem without a unique solution. In this talk, I will show how a set of ultrafast soft X-ray diffraction rocking curves can be spliced together to add constraints to the phase retrieval problem. In doing so, the anti-ferromagnetic order through a NdNiO3 film after illumination of the substrate with a mid-Infrared laser pulse will be imaged. Notably, a disordered phase front initiated at the substrate interface is shown to evolve at twice the speed of sound. This time-spliced imaging technique opens a new window into the correlated dynamics of two-dimensional materials.
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Special Particle Physics Seminar
"Dark Matter Annual Modulation with SABRE"
Presented by Lindsey Bignell, Australian National University
Tuesday, July 31, 2018, 1:30 pm
Small Seminar Room, Bldg. 510Hosted by: David Jaffe
SABRE is a dark matter direct detection experiment with a target of ultra-pure NaI(Tl). Our experiment is motivated by the DAMA result; a long-standing and highly statistically significant modulation of the count rate in their NaI(Tl) detector that is consistent with that expected from the dark matter halo. However, a number of other direct detection experiments, using different target materials, exclude the dark matter parameter space implied by DAMA for the simplest WIMP-nucleus interaction models. SABRE hopes to carry out the first model-independent test of the DAMA claim, with sufficient sensitivity to confirm or refute their result. SABRE will also operate identical detectors in the northern and southern hemisphere, to rule out seasonally-modulated backgrounds. The southern detector will be housed at the first deep underground laboratory in the Southern Hemisphere: the Stawell Underground Physics Laboratory. This talk will give an overview of the SABRE design and its predicted sensitivity, as well as an update on the proof-of-principle detector which will be operating this summer.
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Sambamurti Lecture
"Capturing the Inner Beauty of the Quark Gluon Plasma"
Presented by Jin Huang, Brookhaven National Laboratory
Friday, July 27, 2018, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: John Haggerty
The Quark Gluon Plasma (QGP) filled the universe in the first microsecond after the Big Bang and today is routinely recreated in high energy nuclear collisions at RHIC and the LHC. While experiments have revealed an array of surprising QGP properties, such as perfect fluidity, extreme vorticity, and near total opaqueness to hard scattered quarks and gluons, the detailed physics that gives rise to these properties remains a focus of forefront research. Heavy quarks, particularly the very heavy beauty quark, provide the means to clarify the connection between the microscopic physics of the QGP and its larger scale properties. Beauty quarks – or b-quarks – are produced rarely in collisions at RHIC, and the planned sPHENIX experiment will be equipped with a high rate vertex tracker enabling precision measurements of b-quark observables, such as B-meson suppression and flow, the differential suppression of Upsilon states and a number of observables related to b-quark jets. These b-quark probes will provide crucial information about the microscopic description of QGP at RHIC energies. In this talk, I will explain b-quark physics in the QGP, current measurements, the program at the planned sPHENIX experiment and its relevance to the future Electron Ion Collider.
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Nuclear Theory/RIKEN Seminar
"Jets as a probe of transverse spin physics"
Presented by Zhongbo Kang, UCLA
Friday, July 27, 2018, 2 pm
Building 510, CFNS Seminar Room 2-38Hosted by: Chun Shen
Jets are collimated spray of hadrons that are naturally produced in high energy colliders. They are powerful probes of many different aspects of QCD dynamics. In this talk, we will demonstrate how to use jets to explore the transverse momentum dependent (TMD) physics. A novel TMD framework to deal with back-to-back two particle correlations is presented, with which we could study the Sivers asymmetry for photon+jet or dijet production in transversely polarized proton-proton collisions. At the end of the talk, we also show how jet substructure could be used to explore the TMD fragmentation functions. We expect these studies to have important applications at RHIC in the future.
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Nuclear Theory Seminar
"Medium Modification of Jet Substructure in the Opacity Expansion"
Presented by Matthew Sievert, Los Alamos
Friday, July 27, 2018, 11 am
Building 510, CFNS Seminar Room 2-38Hosted by: Yacine Mehtar-Tani
The modification of jets and their substructure in the presence of quark-gluon matter, beyond solely the quenching of their production, is a cornerstone of jet tomography. Although the nature of different nuclear environments can vary widely, the manner in which an external potential leads to a modification of jets and their substructure is universal and applies to both hot and cold nuclear matter. An order-by-order calculation of the medium modifications is possible on the basis of the opacity expansion, a series which can be truncated at finite order if the average number of scatterings in the quark-gluon matter is not too large. Other methods exist which can resum the full opacity series into a path integral formalism that remains applicable at very high opacities. In this talk, I will present a new calculation in the opacity expansion approach which computes the gluon substructure of a quark jet with exact kinematics at second order in opacity. I will also derive a set of recursion relations which can be used to construct higher orders terms in the opacity expansion to any finite order. And finally, I will compare this approach to the resumed path integral formalism, discussing the strengths and weaknesses of both methods and opportunities to study their overlap.
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Condensed-Matter Physics & Materials Science Seminar
"Atomic level structural characterization of materials by electron microscopy"
Presented by Shize Yang, Center for Functional Nanomaterials
Thursday, July 26, 2018, 4 pm
Bldg. 480, Conference RoomHosted by: Yimei Zhu
In recent years, with the development of technologies, electron microscopy techniques have been widely developed. Important advancement has been achieved on in-situ electron microscopy, cryogenic electron microscopy, electron tomography, advanced electron energy loss spectroscopy etc. In this talk I will briefly introduce and show how those techniques provide a vital role in the structural characterization of 2D materials, catalysts and battery materials.
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Nuclear Theory Seminar
"Jet fragmentation in a QCD plasma: Universal quark/gluon ratio and wave turbulence"
Presented by Soeren Schlichting, University of Washington
Thursday, July 26, 2018, 11 am
Building 510, CFNS Seminar Room 2-38Hosted by: Yacine Mehtar-Tani
We investigate the radiative break-up of a highly energetic quark or gluon in a high-temperature QCD plasma. Within an inertial range of momenta T
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Chemistry Department Seminar
"Triggered Reversible Phase Transformation between Layered and Spinel Structure via Intercalated Hetero Species in Sodium Birnessite"
Presented by Yong-Mook Kang, Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul, 04620, Republic of Korea., Korea, Republic of (South)
Monday, July 23, 2018, 11 am
Room 300, 3rd Flr. Chemistry Bldg. 555Hosted by: Xiao-Qing Yang
Phase transformation of layered structure into spinel structure has been detrimental for most of layered oxide cathodes. Even if a lot of efforts have been made to relieve this highly irreversible phase transformation, there have been few successful results. However, we firstly observed the possibility to make this irreversible phase transformation extremely reversible by utilizing Na- birnessite (NaxMnO2•yH2O; Na-bir) as a basic structural unit, which has distinctive layered structure containing crystal water. Herein, the crystal water in the structure contributes to generating metastable spinel-like phase, which is the key factor for making this unusual reversibility happen. The reversible structural rearrangement between layered and spinel-like phases during electrochemical reaction could activate new cation sites and enhance ion diffusion with higher structural stability. This unprecedented reversible phase transformation between spinel and layered structure was deeply analyzed via combined ex situ soft and hard X-ray absorption spectroscopy (XAS) analysis with in situ X-ray diffraction (XRD). Fundamental mechanism on this reversible phase transformation was theoretically elucidated and confirmed by kinetic investigation using first-principle calculation. These results provide deep insight into novel class of intercalating materials which can deal with highly reversible framework changes, and thus it can pave an innovative way for the development of cathode materials for next- generation rechargeable batteries.
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HET Special Seminar
"The Quest for Dark Sectors"
Presented by Claudia Frugiuele, Weizmann
Friday, July 20, 2018, 10 am
Small Seminar Room, Bldg. 510Hosted by: Sally Dawson
Dark sectors are ubiquitous in physics beyond the Standard Model (SM), and may play a role in explaining many of the long-standing problems of the SM such as the existence of dark matter or the electroweak hierarchy problem. By definition, dark sectors are not charged under any of the known forces. Discovering their possible existence is thus challenging. I will describe how a a broad program combining particle, nuclear and atomic physics experiments can effectively probe a large region of the parameter space. I will show how the unique signatures of such physics can already be searched for with existing/planned experiments, including neutrino-proton fixed-target experiments and precision atomic measurements.
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Environmental & Climate Sciences Department Seminar
"Invariant and insensitive: climate model microphysics as a scaling problem"
Presented by Mikael Witte, National Center for Atmospheric Research
Thursday, July 19, 2018, 11 am
Conference Room Bldg 815EHosted by: Yangang Liu
Clouds are inherently multiscale phenomena: the particles that make up clouds are typically microns to millimeters, while the large-scale circulations that drive cloud systems can be hundreds of kilometers across. Limited computational power and the need to accurately represent the large-scale circulations in numerical simulations of the atmosphere make explicit inclusion of cloud microphysics a practical impossibility. In the last 20 years there has been a shift toward representing microphysics as scale-aware processes. Despite this shift, many unanswered questions remain regarding the scaling characteristics of microphysical fields and how best to incorporate that information into parameterizations. In this talk, I will present results from analysis of high frequency in situ aircraft measurements of marine stratocumulus taken over the southeastern Pacific Ocean aboard the NCAR/NSF C-130 during VOCALS-REx. First, I will show that cloud and rain water have distinct scaling properties, indicating that there is a statistically and potentially physically significant difference in the spatial structure of the two fields. Covariance of cloud and rain is a strong function of length/grid scale and this information can easily be incorporated in large-scale model parameterizations. Next I will show results from multifractal analysis of cloud and rain water to understand the spatial structure of these fields, the results of which provide a framework for development of a scale-insensitive microphysics parameterization. Finally, I compare observed microphysical scaling properties with those inferred from large eddy simulations of drizzling stratocumulus, applying the same analyses as applied to the aircraft observations. We find that simulated cloud water agrees well with the observations but the drizzle field is substantially smoother than observed, which has implications for the ability of limited-area models to adequately reproduce the spatial structure o
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