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JUL
27
Thursday
Environmental & Climate Sciences Department Seminar
"Classifying Aerosol Particles with a Centrifugal Particle Mass Analyzer (CPMA)"
Presented by Kristen Okorn, Stevens Institute of Technology (SULI Student Summer 2017)
11 am, Conference Room Bldg 815E
Thursday, July 27, 2017, 11:00 am
Hosted by: 'Ernie Lewis'
Although wood stoves are a carbon-neutral renewable energy source, they are the largest source of particulate matter (PM) emissions in New York State. A Differential Mobility Analyzer (DMA), which classifies particles by their mobility diameter, has traditionally been employed to characterize such particulate emissions. However, because the black carbon (BC) particles produced by combustion that contribute to PM are fractal, their mobility diameters are not equal to their mass-equivalent diameters. In contrast to the DMA, the Centrifugal Particle Mass Analyzer (CPMA) classifies aerosol particles by their mass, using two rotating cylinders and an electric potential; when the centrifugal and electrostatic forces on a particle are equal, it passes through. The CPMA can select particles with masses ranging from 2×10 4 to 1.05×103 fg (corresponding to diameters, for particles with density 1 g cm 3, ranging from 7 to 1300 nm). It can be operated in two different ways: the "Run" classification method can be used to select for a single particle mass, and the "Step Scan" method can be used to select particles over a set range of masses. A neutralizer must be used upstream of the CPMA to create a charge distribution on particles before they enter the instrument. A DMA can optionally be used to pre-select particles of a specific mobility diameter before entering the CPMA. Downstream of the instrument, a Condensation Particle Counter (CPC) must be used in order to determine the number concentration of particles that pass through the CPMA. The basic operating principles of the CPMA are discussed, and results are presented for its characterization of polystyrene latex (PSL) particles, ammonium sulfate particles, and emissions from a wood burning stove.
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JUL
27
Thursday
Computational Science Initiative Event
"The AMReX Astrophysics Suite: Simulating the Stars at the Exascale"
Presented by Michael Zingale, Associate Professor, Dept. Of Physics and Astronomy, Stony Brook University
1:30 pm, Seminar Room, Bldg. 725
Thursday, July 27, 2017, 1:30 pm
Hosted by: 'Meifeng Lin'
Astronomy is an observational science — we take data (primarily light) from the objects in the Universe and use this to infer how systems work. Astrophysical simulations allow us to perform virtual experiments on these systems, giving us the ability to see into stars in a way that light alone does not allow. Stellar systems can be modeled using the equations of hydrodynamics, together with nuclear reactions, self-gravity, complex equations of state, and at times, radiation (and magnetic fields). The resulting simulation codes are multiphysics and multiscale, and a variety of techniques have been developed to permit accurate and efficient simulations. We describe the adaptive mesh refinement (AMR) codes for astrophysics built upon the AMReX library: the AMReX Astrophysics Suite. We'll focus on the codes for stellar / nuclear astrophysics: Maestro and Castro. Maestro models subsonic stellar flows while Castro focuses on highly-compressible flows. They share the same microphysics (reaction networks, equations of state) and parallelization strategy. Through AMReX, we distribute boxes in our AMR hierarchy across nodes and we use OpenMP (via a logical tiling model in Castro) to spread the work on a box across cores in a node. Recently we've implemented a GPU strategy in AMReX that allows us to move the computational kernels onto GPUs to offload expensive calculations. We'll discuss the current performance of the hydrodynamics and reaction networks on GPUs and how our strategy will evolve in the future.
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JUL
27
Thursday
Particle Physics Seminar
"Latest Results from NOvA"
Presented by Louise Suter, Fermilab
3 pm, Small Seminar Room, Bldg. 510
Thursday, July 27, 2017, 3:00 pm
Hosted by: ''Xin Qian''
NOvA is a long-baseline neutrino experiment which utilizes two basically fully active, finely segmented, liquid scintillator detectors: a Near Detector located at Fermilab, and a Far Detector located in Ash River, MI, and situated roughly 14 mrad off Fermilab's NuMI beam. Using this narrow-band beam of mostly muon neutrinos we study the oscillation of these neutrinos over the 810 km baseline to measure the rate of electron neutrino appearing and of muon neutrinos and neutral current interactions disappearing between the two detectors. These are interpreted to give our latest measurements on the neutrino mass ordering, CP violation, the flavor content of the third neutrino mass eigenstate, and tests of the three-neutrino paradigm.
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AUG
2
Wednesday
Brookhaven Women In Science Lecture
"Renate W. Chasman Awards"
11:30 am, Large Seminar Room, Bldg. 510
Wednesday, August 2, 2017, 11:30 am
Please join us as we award the Chasman Scholarship to Tiffany Victor, Stony Brook University, and Hannah Herde, Brandeis University. Both awardees will give a talk. Lunch will be provided. Sponsored by Brookhaven Women in Science.
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AUG
2
Wednesday
BSA Noon Recital
"Pianofest"
12 pm, Berkner Hall Auditorium
Wednesday, August 2, 2017, 12:00 pm
Hosted by: 'Geoffrey Hind'
Pianofest in the Hamptons sends a group of workshop participants from its second session to perform from the great classical piano repertoire. Solo works, duets and concerto movements (using two pianos) may be presented.
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AUG
16
Wednesday
Computational Science Initiative Event
"From Data to Discovery: Accelerated Search for Materials with Targeted Properties"
Presented by Turab Lookman, Los Alamos National Laboratory
11 am, Seminar Room, Bldg. 725
Wednesday, August 16, 2017, 11:00 am
Hosted by: 'Frank Alexander'
Next generation experimental facilities will offer unprecedented access to understanding in situ bulk materials behavior and generate data at higher rates than possible today. A key aspect is learning from the data to overcome challenges in analysis and discover new materials. Needed are tools that will seamlessly integrate data with inference and theory, where available, in a codesign loop for guiding experiments. Central to this is the use of uncertainties to explore the search space to minimize he number of iterations needed for the search. I will review some of our recent work directed towards finding for new piezoelectric compositions as well as shape memory alloys, and analysis of diffraction data.
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AUG
23
Wednesday
Condensed-Matter Physics & Materials Science Seminar
"Experiments on electron hydrodynamics with and without applied magnetic fields"
Presented by Andrew Mckenzie, Max-Planck-Institute, Germany
1:30 pm, Bldg. 734, ISB Conf. Room 201 (upstairs)
Wednesday, August 23, 2017, 1:30 pm
Hosted by: ''Cedomir Petrovic''
Will discuss experiments aimed at probing signatures of viscous contributions to electrical transport in ultra pure metallic systems. The hydrodynamic regime was reached in semiconductor heterostructures in the 1990s, but has only recently come into reach in naturally occurring compounds. I will focus on our group's work on layered delafossite metals, but possibly also discuss results from other groups on different material families.
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AUG
31
Thursday
Particle Physics Seminar
"Wiener-SVD approach to data unfolding"
Presented by Dr. Hanyu Wei, BNL
3 pm, Small Seminar Room, Bldg. 510
Thursday, August 31, 2017, 3:00 pm
Hosted by: 'Xin Qian'
Data unfolding is a commonly used technique in the high energy physics experiments, to retrieve the distorted or transformed measurements by various detector effects. Inspired by the deconvolution technique in the digital signal processing, a new unfolding technique based on the Singular Value Decomposition (SVD) of the response matrix is developed. With the well-known Wiener filter concept, the modified SVD approach, Wiener-SVD, achieves the maximizing signal-to-noise ratio of the binned data in a transformed set of orthonormal bases where the uncertainties are bin-to-bin uncorrelated. In this talk, the mathematical principles and formulations of the newly developed Wiener-SVD unfolding will be presented. A few applications will be demonstrated. A comparison with the commonly used regularization method will also be shown. The advantages and disadvantaged of the Wiener-SVD approach will be discussed.
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SEP
7
Thursday
Particle Physics Seminar
"Radiation damage study of a thin YAG:Ce scintillator using low-energy protons"
Presented by Dr. Vladmir Linhart, Czech Technical University in Prague
3 pm, Small Seminar Room, Bldg. 510
Thursday, September 7, 2017, 3:00 pm
Hosted by: '''Xin Qian'''
Radiation hardness of a 50µm thin YAG:Ce scintillator in a form of dependence of a signal efficiency on 3.1MeV proton ?uence was measured and analyzed using X-ray beam. The signal efficiency is a ratio of signals given by a CCD chip after and before radiation damage. The CCD chip was placed outside the primary beam because of its protection from damage which could be caused by radiation. Using simplified assumptions, the 3.1MeV proton fluencies were recalculated to: • 150 MeV proton fluencies with intention to estimate radiation damage of this sample under conditions at proton therapy centers during medical treatment, • 150 MeV proton doses with intention to give a chance to compare radiation hardness of the studied sample with radiation hardness of other detectors used in medical physics, • 1 MeV neutron equivalent fluencies with intention to compare radiation hardness of the studied sample with properties of position sensitive silicon and diamond detectors used in nuclear and particle physics. The following results of our research were obtained. The signal efficiency of the studied sample varies slightly (±3%) up to 3.1MeV proton ?uence of c. (4 − 8) × 1014 cm−2. This limit is equivalent to 150MeV proton ?uence of (5 − 9) × 1016 cm−2, 150MeV proton dose of (350 − 600) kGy and 1MeV neutron ?uence of (1 − 2) × 1016 cm−2. Beyond the limit, the signal efficiency goes gradually down. Fifty percent decrease in the signal efficiency is reached around 3.1MeV ?uence of (1 − 2) × 1016 cm−2 which is equivalent to 150 MeV proton ?uence of around 2 × 1018 cm−2, 150MeV proton dose of around 15 MGy and 1 MeV neutron equivalent ?uence of (4 − 8) × 1017 cm−2. In contrast with position sensitive silicon and diamond radiation detectors, the studied sample has at least two order of magnitude greater radiation resistance. Therefore, YAG:Ce sci
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SEP
7
Thursday
CFN Colloquium
"First-Principles Theory of Epitaxial Film Growth"
Presented by Shangbai Zhang, Department of Physics, Applied Physics, & Astronomy, Rensselaer Polytechnic Institute
4 pm, CFN, Bldg 735, Seminar Room 2nd Floor
Thursday, September 7, 2017, 4:00 pm
Hosted by: ''Deyu Lu''
First-principles studies often rely on the assumption of equilibrium, which can be a poor approximation, e.g., for epitaxial growth. Here, we propose a general effective chemical potential (μ ¯) approach for non-equilibrium systems. It incorporates growth kinetics into the chemical potential, while maintaining its correct equilibrium limits. In studying molecular beam epitaxy (MBE), we divide the process into three stages: pre-nucleation, nucleation, island growth, and focus our efforts on the first two. For the pre-nucleation stage, we solve the rate equations for small clusters on the surface, which serve as the feedstock for the growth, and find that μ ¯ is determined by the most probable, rather than by the lowest-energy, clusters. While this finding contradicts the equilibrium theory (which is in favor of the lowest-energy state), it reinforces the fundamental principle of statistic mechanics. In the case of Bi2Se3, μ ¯ is found to be highly supersaturated. As μ ¯ determines the nucleation barrier for the nucleation stage, this supersaturation leads to a high nucleus concentration and small-sized islands, in qualitative agreement with experiment.
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SEP
16
Saturday
BNL Team at Port Jeff Dragon Boat Race Festival
"BERA Team organized by the APAA"
9 am, Port Jefferson Harborfront Park
Saturday, September 16, 2017, 9:00 am
Hosted by: 'Asian Pacific American Association'
The BERA Asian Pacific American Association is participating in the 2017 Port Jefferson Dragon Boat Race Festival on Saturday, Sept. 16th. At this festival, local and regional teams compete in a series of heats. Novice teams are provided with instruction and all of the necessary equipment to race.
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OCT
16
Monday
Condensed-Matter Physics & Materials Science Seminar
"Domain walls and phase boundaries - new nanoscale functional elements in complex oxides"
Presented by Jan Seidel, UNSW Sydney
1:30 pm, Bldg. 480, Conference Room
Monday, October 16, 2017, 1:30 pm
Hosted by: 'Yimei Zhu'
Topological structures in functional materials, such as domain walls and skyrmions, see increased attention due to their properties that can be completely different from that of the parent bulk material [1]. I will discuss recent results on multiferroic phase boundaries, domain walls in BiFeO3 [2, 3, 4, 5, 6] using SPM, TEM and ab-initio theory, and discuss future prospects [7]. References [1] J. Seidel (ed.), Topological structures in ferroic materials: domain walls, skyrmions and vortices, ISBN: 978-3-319-25299-5, Springer, Berlin (2016) [2] P. Sharma, et al., Scientific Reports 6, 32347 (2016) [3] P. Sharma, et al., Advanced Electronic Materials 2, 1600283 (2016) [3] J. Seidel, et al., Advanced Materials 26, 4376 (2014) [4] Y. Heo, et al., Advanced Materials 26, 7568 (2014) [5] Y. Heo et al., ACS Nano, DOI: 10.1021/acsnano.6b07869 (2017) [6] P. Sharma, et al., Advanced Materials Interfaces 3, 1600033 (2016) [7] J. Seidel, Nature Nanotechnology 10, 190 (2015)
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NOV
2
Thursday
CFN Colloquium
"Synthesis, Characterization, and Applications of Nanocomposite Coatings with Tunable Properties Prepared by Atomic Layer Deposition"
Presented by Jeffrey Elam, Argonne National Laboratory
4 pm, CFN, Bldg 735, 2nd Floor Seminar Room
Thursday, November 2, 2017, 4:00 pm
Hosted by: ''Chang-Yong Nam''
We have been developing atomic layer deposition (ALD) nanocomposite coatings comprised of conducting, metallic nanoparticles embedded in an amorphous dielectric matrix. These nanocomposite films have proved to be exceptional as resistive coatings in solid-state electron multipliers, as charge drain coatings, and as solar absorbing films in concentrated solar power. All of these applications demand tunable properties so that particular attributes of the film, such as electronic resistivity, can be precisely tailored for maximum efficiency. In our films, the properties are tuned by adjusting the ratio of metallic and dielectric components. For example, nanocomposite films comprised of W:Al2O3 are prepared using alternating exposures to trimethyl aluminum (TMA) and H2O for the Al2O3 ALD and alternating WF6/Si2H6 exposures for the W ALD. By varying the ratio of ALD cycles for the W and the Al2O3 components in the film, we can tune precisely the resistance of these coatings over a very broad range from 1012-105 Ohm-cm. We have used this strategy to synthesize a broad range of ALD nanocomposites combining different metals and dielectrics. These nanocomposite coatings have been utilized to functionalize capillary glass array plates and fabricate large-area microchannel plates suitable for application in large-area photodetectors. In addition, we have applied these films to serve as charge drain coatings in micro electro-mechanical systems (MEMS) devices for a prototype electron beam lithography tool, and obtained high-resolution electron beam patterns without charging artifacts. We have also used these nanocomposite coatings to infiltrate porous scaffolds resulting in selective solar absorbing coatings with high visible absorption and low IR emittance suitable for power tower receivers in concentrated solar power.
