Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session L15: Computational Physics II |
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Sponsoring Units: DCOMP Chair: Tim Germann, Los Alamos National Laboratory Room: Plaza Court 4 |
Sunday, April 14, 2013 3:30PM - 3:42PM |
L15.00001: Improving general relativistic astrophysics workflows with ADIOS Tanja Bode, Magdalena Slawinska, Jeremy Logan, Michael Clark, Matthew Kinsey, Matthew Wolf, Scott Klasky, Pablo Laguna There are many challenges in analyzing and visualizing data from current cutting-edge general relativistic astrophysics simulations. Many of the associated tasks are time-consuming, with large performance degradation due to the magnitude and complexity of the data. The Adaptable IO System (ADIOS) is a componentization of the IO layer that has demonstrated remarkable IO performance improvements on applications running on leadership class machines while also offering new in-memory ``staging'' operations for transforming data in situ. We have incorporated ADIOS staging technologies into our Maya numerical relativity code based on Cactus infrastructure and Carpet mesh refinement. We present results that demonstrate how ADIOS yields significant gains on IO performance while utilizing leveraged investments in ADIOS plugins for visualization tools such as VisIt. [Preview Abstract] |
Sunday, April 14, 2013 3:42PM - 3:54PM |
L15.00002: The Noble Element Simulation Technique (NEST) Michael Woods A comprehensive model for explaining the mean scintillation and electroluminescence yields in liquid and gaseous noble elements will be presented which informs an exhaustive simulation code called NEST (Noble Element Simulation Technique). All available liquid xenon data on electron and nuclear recoils have been incorporated, and significant progress has been made on extending NEST's applicability to argon. Results will be shown from Geant4 implementations for 1- and 2-phase xenon and argon detectors. The quasi-empirical NEST approach can lead to a better understanding of detector calibrations and performance verification and aid in the design and optimization of future detectors for dark matter or other applications, and assist in the data analysis stage of present detectors. [Preview Abstract] |
Sunday, April 14, 2013 3:54PM - 4:06PM |
L15.00003: Modeling the Energy Resolution of Xenon with NEST Sergey Uvarov In addition to explaining the mean yields, NEST (the Noble Element Simulation Technique) can also address the energy resolution degrading effects in noble elements, for both electron and nuclear recoils (ER and NR). Liquid and gaseous xenon will be presented as examples. A non-binomial recombination fluctuation model will be discussed which well describes the intrinsic, supra-Poissonian resolution observed in xenon. It is combined with electric field effects, the Fano factor, and detector efforts, such as finite light collection efficiency and PMT quantum efficiency. In matters of conflicting dark matter search results observed by experiments such as XENON100 and CoGeNT, a stochastic, non-analytic, partially non-Gaussian understanding of the energy resolution for low-energy, WIMP-like nuclear recoils may be part of the solution. ER-NR discrimination can be predicted well with such an understanding. [Preview Abstract] |
Sunday, April 14, 2013 4:06PM - 4:18PM |
L15.00004: Pulse Shape in 2-Phase Xenon Detectors Jeremy Mock Understanding the shape and size of the primary (S1) and secondary (S2) scintillation pulses in noble elements is crucial for discriminating between different particle interactions. Monte Carlo results from NEST (the Noble Element Simulation Technique) will be presented which match the available data from liquid xenon on the dependence of the recombination time, which is a critical piece of the S1 pulse timing structure, on dE/dx, interaction type, and electric field magnitude. In addition, a model for the S2 pulse shape and the dependence of its width on the depth of an interaction in a detector will be presented which takes into account drift speed, the single/triplet time constants, diffusion, thermal electron trapping at a liquid-gas interface, and other effects. [Preview Abstract] |
Sunday, April 14, 2013 4:18PM - 4:30PM |
L15.00005: Classical two-dimensional numerical algorithm for ?-Induced charge carrier advection-diffusion in Medipix-3 silicon pixel detectors Mason Biamonte, John Idarraga A classical hybrid alternating-direction implicit difference scheme is used to simulate two-dimensional charge carrier advection-diffusion induced by alpha particles incident upon silicon pixel detectors at room temperature in vacuum. A mapping between the results of the simulation and a projection of the cluster size for each incident alpha is constructed. The error between the simulation and the experimental data diminishes with the increase in the applied voltage for the pixels in the central region of the cluster. Simulated peripheral pixel TOT values do not match the data for any value of applied voltage, suggesting possible modifications to the current algorithm from first principles. Coulomb repulsion between charge carriers is built into the algorithm using the Barnes-Hut tree algorithm. The plasma effect arising from the initial presence of holes in the silicon is incorporated into the simulation. The error between the simulation and the data helps identify physics not accounted for in standard literature simulation techniques. [Preview Abstract] |
Sunday, April 14, 2013 4:30PM - 4:42PM |
L15.00006: Occupancy Study of the Phase 1 Upgrade to the CMS Pixel Sub-detector James Zabel The Phase 1 Upgrade for CMS includes the installation of a new Pixel detector, complete with newly designed readout chips as well as a new geometry. This upgrade is necessary to replace the existing irradiated Pixel detector with one designed for higher instantaneous luminosities. It also provides an opportunity to improve the resolution of track reconstruction and vertex isolation. The new geometry and the higher beam energies available after the upgrade increase the fluence of ionizing radiation traveling through the Pixel detector. Results of simulations that estimate pixel hits, and thus provide an opportunity to estimate data rates and fluence, will be shown. The simulations incorporate a variety of factors affecting the estimated data rates and fluence, including various luminosities, bunch spacings, and beam spot locations. [Preview Abstract] |
Sunday, April 14, 2013 4:42PM - 4:54PM |
L15.00007: Tests of Pixel Detector Readout Components to be used in the CMS Experiment During Phase I of the LHC Upgrade Indira Vergara-Quispe During Phase I of the LHC upgrade, the CMS pixel detector will need to handle a much higher data volume due to the doubling of the luminosity as well as the planned increase in the number of pixel modules. To meet this challenge the readout scheme will be changed to digital readout and the readout frequency will be increased. The design of the new readout system includes the use of a voltage control oscillator (VCO) and data serializers. The VCO has already been designed and three prototype samples were built and tested. To determine radiation hardness, they were then irradiated with 60Co in 10 doses of 50 KGy each. The serializer has also been designed and studied via simulation to determine its timing performance. Results of these tests and simulations will be presented. [Preview Abstract] |
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