Bulletin of the American Physical Society
83rd Annual Meeting of the APS Southeastern Section
Volume 61, Number 19
Thursday–Saturday, November 10–12, 2016; Charlottesville, Virginia
Session J1: Particle Physics II |
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Chair: Craig Group, University of Virginia Room: West Ballroom |
Friday, November 11, 2016 3:45PM - 3:57PM |
J1.00001: Pion Charge Exchange Cross Section on Liquid Argon Kevin Nelson The observation of neutrino oscillations allows charge parity violation to be probed in the neutrino sector. Detectors with high calorimetric energy resolution and high spatial resolution will provide precise measurements of neutrino oscillations. By measuring small $\pi^\pm$ cross sections for individual interaction channels, specifically charge exchange, we will make a measurement in the first of its kind on liquid Argon and demonstrate the physics capabilities of a relatively new detector technology: the Liquid Argon Time Projection Chamber (LAr TPC). This analysis will report on the thin slab cross section measurement technique and the Monte Carlo cross section measurements in the energy range of 0.2 - 1.0 GeV. This analysis is the first iteration in classifying charge exchange events from a sample of incident pions, and it aims to identify events in which a $\pi^0$ was produced without any charged pions leaving the interaction vertex. We will also report on the methodology and efficiency of this algorithm in identifying particles and their interactions in liquid argon. This analysis will inform a future measurement of the $\pi^\pm$ charge exchange cross section on liquid argon. [Preview Abstract] |
Friday, November 11, 2016 3:57PM - 4:09PM |
J1.00002: Geant4 Monte Carlo Simulations of PEN Experiment Charles Glaser The PEN experiment performed at the Paul Scherrer Institute is a precision measurement of $\pi^+\rightarrow e^+\nu_e(\gamma)$ branching ratio with the goal of obtaining a relative uncertainty of $5\times10^{-4}$ or less. The ratio of decay rates $\Gamma(\pi\rightarrow e\bar{\nu}(\gamma))/\Gamma(\pi\rightarrow \mu \bar{\nu}(\gamma))$ provides a key confirmation of the V$-$A nature of the electroweak interaction. The detector apparatus consisted of active beam and target counters, a mini-time projection chamber and multi-wire proportional chamber for beam and decay particle tracking, a plastic scinitillator for particle identification and a spherical CsI electromagnetic calorimeter. The Geant4 Monte Carlo simulation is used to calibrate energy spectra, obtain the acceptances of the experiment, and more fully comprehend background events. Ultra realistic events are generated by placing detector elements correctly at the sub-millimeter level, recreating the beam profile, accounting for noise and photo electron statistics, and producing synthetic waveforms and digitized outputs. Proper simulation ultimately leads to more reliable discrimination of background events, thereby improving cut based or multivariate branching ratio extraction. [Preview Abstract] |
Friday, November 11, 2016 4:09PM - 4:21PM |
J1.00003: Comparison of two methods of parallelizing GEANT4 on beowulf computer cluster Seth Hulsey, Ivan Novikov Numerical techniques for problem solving have become an integral part of theoretical science and mathematical modeling. However, the rate of improvement of computer processor speeds have begun to plateau. Parallel and distributed computing have become the standard method to perform computationally expensive calculations. The beowulf cluster, a group of computers connected in a local network, is a simple means of creating a powerful machine for parallel computing. We describe the setup of GEANT4 simulation software on a beowulf cluster using the ROCKS cluster operating system and test two methods of distributing work throughout the cluster: a “frontend-compute node” method using TOP-C and a “static scheduling” method using MPI. [Preview Abstract] |
Friday, November 11, 2016 4:21PM - 4:33PM |
J1.00004: Simulations and Fitting Methods in the Nab Experiment Wenjiang Fan The Nab collaboration at the Spallation Neutron Source (SNS) aims to measure the electron-neutrino correlation parameter $a$ with a relative uncertainty of about $10^{-3}$, and the Fierz interference term $b$ with absolute uncertainty of $3\times 10^{-3}$. Nab will use a novel time-of-flight magnetic field spectrometer to guide the charged decay products to two segmented Si detectors. In the Nab experiment, $a$ is determined by combined precise determinations of the electron energy and the proton time-of-flight. In this talk, we will present a fitting method to analyze $a$, as well as specific techniques developed to increase the simulation speed while keeping the required precision in the Geant 4 simulation. [Preview Abstract] |
Friday, November 11, 2016 4:33PM - 4:45PM |
J1.00005: Developing a Shielding Model for the n, n-bar Experimental Beamline at the European Spallation Source Caleb Redding, L.W. Townsend Under development is a radiation shielding model for the n, n-bar beamline at The European Spallation Source in Lund, Sweden. The size of the beamline adds a layer of complexity to this problem. With the beamline being 200-meters long and having a 4-meter diameter, the problem cannot be solved using Monte Carlo methods in analog mode. Variance reduction techniques must be used in order to approach a statistically sound answer within a reasonable timeframe. In this talk an overview of the problem, variance reduction methods, and current status of the model build will all be provided. [Preview Abstract] |
Friday, November 11, 2016 4:45PM - 4:57PM |
J1.00006: Initial studies of GaInP based Geiger mode APD arrays Victoria Kovalchuk High density Geiger-mode APD (GAPD) arrays, typically manufactured using silicon substrates are widely used in for applications requiring fast and highly efficient detection of photons. Generically called silicon photomultipliers (SiPMs), these are now widely available and offer excellent detection properties, signal to noise, and single photon counting resolution. Wide band gap semiconductors such as GaInP have the potential to survive and maintain performance characteristics over many orders of magnitude larger radiation doses compared to silicon. There is a strong demand for electronics capable of surviving environments with particle fluence for applications in particle physics experiments. New GAPD arrays based on GaInP have been produced by LightSpin Technologies and tested at UVa. We introduce the properties expected of functional GAPD arrays and present results from studies of these new prototype devices including measurements of DC characteristics, noise, single photon response, and a preliminary review of radiation damage studies. [Preview Abstract] |
Friday, November 11, 2016 4:57PM - 5:09PM |
J1.00007: Performance characteristics of GaInP based Geiger mode APD arrays Grace Cummings We present a collection of studies examining the performance of new high density Geiger-mode APD (GAPD) arrays manufactured using GaInP semiconductor technology, including an evaluation of signal and noise characteristics for new prototype devices and preliminary radiation exposure studies. This talk also reviews the physical properties related to each measurement and discusses expectations and physical factors that can affect the performance of manufactured devices. [Preview Abstract] |
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