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JUL
19
Friday
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
19
Friday
** Friday ** ASAP Student & Postdoc Barbecue
5:30 pm, Gazebo by NSLS II & Ball Fields
Friday, July 19, 2019, 5:30 pm
Hosted by: Association of Students & Postdocs ~ ASAP ~
Now on FRIDAY! Get your tickets at the BERA store before Thursday at 2pm, $3pp, or $5 at the door day of. Rain date is Happening for Friday 7/19!!
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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
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.
