Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Y08: Computational Physics |
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Sponsoring Units: DCOMP Room: Sheraton Governor's Square 10 |
Tuesday, April 16, 2019 1:30PM - 1:42PM |
Y08.00001: Towards Robust Methods for Relativistic Neutrino Transport Eirik Endeve We develop methods for simulation of multi-dimensional neutrino transport in nuclear astrophysics applications (e.g., core-collapse supernovae and binary neutron star mergers). |
Tuesday, April 16, 2019 1:42PM - 1:54PM |
Y08.00002: Using Machine Learning Tools to Enhance Background Subtraction at E906/SeaQuest Marshall Scott The SeaQuest experiment studies the flavor asymmetry of the proton through the Drell-Yan process using fixed target collisions from the 120 GeV Main Injector beam at Fermilab. Though the Drell-Yan process is clean, its cross section is minuscule compared to the nuclear cross section. This coupled with the high intensity beam yields significant random background that must be removed. Monte Carlo simulations of Drell-Yan events from the beam dump and targets have been used to develop sets of analysis cuts; Machine learning (ML) has been used to augment these cuts. This presentation will focus on using ML and analysis cuts to process the initial distributions, describe how newer, more powerful discriminating variables were developed, and give a comparison of the ML+Analysis preprocessing results with the standard analysis cuts. |
Tuesday, April 16, 2019 1:54PM - 2:06PM |
Y08.00003: Accelerating NOvA's Feldman Cousins procedure with high performance computing platforms Derek D Doyle When fitting models to data with low statistics and near physical boundaries, additional measures need to be taken to ensure proper statistical coverage. This is especially true in neutrino physics, where neutrino-matter weak interactions are rare. NOvA, a long-baseline neutrino oscillation experiment, aims to measure the parameters governing neutrino oscillations within the PMNS oscillation model. In order to ensure proper statistical coverage, NOvA uses the computationally intensive Feldman-Cousins (FC) procedure. The FC procedure involves fitting thousands of independent pseudoexperiments to generate empirical statistical distributions that are then used to calculate the significance of measurements. Here, work done by NOvA and SciDAC collaborators to implement the FC procedure utilizing the High Performance Computing facilities at NERSC, is presented. With these tools, NOvA’s complete FC corrections for their recent neutrino + antineutrino appearance analysis were processed in 36 hours: a speedup factor of 50 when compared to the methods used in previous analyses. |
Tuesday, April 16, 2019 2:06PM - 2:18PM |
Y08.00004: Benefits of the Sirepo cloud computing framework for graduate level physics education David L Bruhwiler, Robert Nagler, Paul Moeller, Christopher Hall, Nathan M Cook, Dan T Abell, Boaz Nash, Michael Keilman The Sirepo framework provides browser-based GUIs for particle accelerator modeling, X-ray beamlines, and other physical systems [1,2]. Such simulation codes require time and training to learn a command-line workflow involving multiple input and configuration files, execution on a high-performance server or cluster, post-processing with specialized software and finally visualization. The Sirepo framework is being developed to make state of the art codes available in the browser of any desktop, laptop or tablet. This work is facilitating education of graduate students and enabling instantaneous sharing of simulation details between colleagues. Sirepo enables any code with a command-line interface to be brought to the cloud, automatically providing features that enable subsequent use with students. We discuss initial results from using Sirepo-based apps in the classroom. |
Tuesday, April 16, 2019 2:18PM - 2:30PM |
Y08.00005: Computational Study of Double Ionization in Intense Bicircular Fields Jan Lucien Chaloupka Since the discovery of multiphoton, multiply charged ionization 35 years ago, the study of double ionization in intense laser fields has been foundational in the development of strong-field physics. In the rescattering model, the Coulomb potential of the atom is distorted by the laser field, leading to liberation of an electron through tunneling. This electron gains energy from the laser field and is driven back to the ion, where it can help free a second electron via impact ionization. Since this process relies on trajectories that bring the first electron back to the ion, it is most effective with linear polarization, and is reduced significantly with increased ellipticity. But it has been shown that a bicircular laser pulse, generated by combining two colors with counter-rotating circular polarization, can also lead to effective double ionization. We recently investigated the dynamics of these processes with a computational study utilizing a classical ensemble [PRL 116, 143005 (2016)]. Here, we present new results generated with a high-performance computational cluster, uncovering novel patterns in recollision timing, identifying classes of complex trajectories that contribute to double ionization, and demonstrating that rescattering can occur even in co-rotating fields. |
Tuesday, April 16, 2019 2:30PM - 2:42PM |
Y08.00006: Efficient calculation of ground state properties of strongly correlated fermionic systems with BCS-Constrained-Path Auxiliary-Field Quantum Monte Carlo Ettore Vitali, Peter Rosenberg, Shiwei Zhang We introduce an efficient and numerically stable technique to compute ground state correlation functions of strongly correlated physical systems within the Constrained-Path Auxiliary-Field Quantum Monte Carlo relying on a BCS trial wave function. Whenever the sign problem is absent, the methodology provides exact ground state properties. When the sign problem is present, on the other hand, the BCS wave function provides a powerful generalization of the usual Constrained-Path Auxiliary-Field Quantum Monte Carlo technique which relies on Slater Determinants. We present benchmark results for the attractive Hubbard model, comparing with exact diagonalization, including the case where a finite spin polarization is present. We also present results for the repulsive Hubbard model, in connection with d-wave pairing superconductivity. |
(Author Not Attending)
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Y08.00007: A Mathematical Model for the Holistic Medicine Part 1 Christina Pospisil, Tong Shu In this work we present a mathematical model for the transformation of information entering the teeth and travelling to the organs. More precisely: (Food) Particles hitting teeth and how this information is transformed into electrical information inside the body. Moreover, we give an experimental overview to test and verify the model in our future work. Depending on experiments we can probably already present some results of experiments in April. Furthermore, for future work we will continue modelling the information interaction from the outside to the inside of the body and how this affects the human body. |
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