Bulletin of the American Physical Society
2018 Joint Spring Meeting of the Texas Sections of APS, AAPT, and Zone 13 of the SPS
Volume 63, Number 8
Thursday–Saturday, March 22–24, 2018; Stephenville, Texas
Session G3: APS IV - High Energy & Nuclear Physics |
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Chair: Daniel Marble, Tarleton State University Room: Science 102 |
Saturday, March 24, 2018 10:30AM - 10:42AM |
G3.00001: Machine learning to identify top quarks for BSM searches Kenneth Call, Jay Dittmann, Kenichi Hatakeyama, Nathaniel Pastika Many scenarios of physics beyond the standard model lead to final states involving a top quark, and its identification can play an important role. I will present a tagging method to identify tops quarks that decay into 3 separately resolved hadronic jets. This method complements other types of top quark identification, and is especially helpful in the case of low momentum top quarks. The tagger makes use of a neural network with both Recurrent Neural Network (RNN) and Dense Neural Network (DNN) elements. This tagger is applied in a search for supersymmetric particles in events with multiple top quarks and missing transverse energy. The search is based on proton-proton collisions collected with the CMS detector at the CERN LHC at a center of mass energy of 13 TeV. [Preview Abstract] |
Saturday, March 24, 2018 10:42AM - 10:54AM |
G3.00002: Simulating the Electric Field for the Proto-DUNE Dual Phase Detector Mathew Rapp The Proto-DUNE Dual Phase Detector is a prototype for DUNE, the Deep Underground Neutrino Experiment. This Dual Phase Liquid Argon TPC operates as one of two prototypes for the far detector used for the DUNE experiment. The detector is housed within a cryogenic structure submerged in 300t of Liquid Argon. A uniform electric field of 500 volts per centimeter is maintained within the active space of the detector by large voltage differences across 98 aluminum profiles. Simulations of the electric field allow for the behavior of the detector to be studied before it becomes operational. The geometry used to simulate the detector can be manipulated to test for tolerances of its components. A large source of error for this experiment is the buildup of charges on the surface of the detectors components. Simulations computed to assist in identifying where this might occur within the detector. Hence, performing these simulations is vital to understand and anticipate how specific parts will affect the detectors performance. These simulations will be of use to both Proto-DUNE modules, as well as future projects involving LArTPC technology. [Preview Abstract] |
Saturday, March 24, 2018 10:54AM - 11:06AM |
G3.00003: Design and testing of High Voltage Divider Board for ProtoDUNE Dual Phase Field Cage Douglas Zenger The ProtoDUNE dual-phase is a prototype of the Deep Underground Neutrino Experiment (DUNE), which will be operating at CERN. With 98 aluminum profiles and supported by FRP I-beams, the field cage will be submerged in liquid argon with gaseous argon above it. A neutrino will interact with a liquid argon's electron, and the electron is detected in the gaseous argon. A strong, uniform electric field of 500V/cm will cause the electron to drift upwards, requiring a voltage of 300kV at the cathode at the bottom. To connect profiles electrically and to distribute the field uniformly , resistors and varistors will be placed on a divider board, where resistors divide the voltages uniformly across the detector active volume, and varistors protect the resistors from potential electrical surges. Four 2G$\Omega $ resistors and two groups of four varistors in series are placed in parallel between each profile. The Boards will consist of pretested parts and then assembled. Testing will ensure the quality of the parts using liquid argon. The divider board has been tested in room temperature, liquid nitrogen, and mounted on a field cage. Testing occurs by testing both individual stages and whole boards up to 6kV potentials. [Preview Abstract] |
Saturday, March 24, 2018 11:06AM - 11:18AM |
G3.00004: Observation of the behavior of radiation sources with GEM. Jakob Scantlin The gas electron multiplier, or GEM, is a device used for amplifying electrons released from ionization of argon gas. The GEM foil is constructed of a polymer clad in a thin layer of copper on either side with small holes chemically etched in a hexagonal matrix pattern. A high voltage is applied across the foil to produce a concentrated electric field between the holes to accelerate the electrons. The gas is placed between the foil and the induction layer, which is where the readout electronics are. Once the electrons are accelerated through the electric field, they ionize more argon gas atoms to release even more electrons (about 100 times more). The purpose of the GEM is to amplify the signals from ionization events so the currents read by the readout electronics can be large enough to accurately measure. An oscilloscope is used to show ionization events of different radiation sources such as Cs-137 or Fe-55. [Preview Abstract] |
Saturday, March 24, 2018 11:18AM - 11:30AM |
G3.00005: Robustness of DUNE Field Cage Dual-Phase Detector Cristobal Garces UTA's HEP Group oversees the design and construction of the protoDUNE Dual-Phase Field Cage, which is operating at CERN. Dual-Phase LArTPC's are one of the far detector technology options foreseen for the Deep Underground Neutrino Experiment (DUNE). The Field Cage is designed to be supported by I-Beams and is connected to the ceiling of the cryostat. The primary I-beams need to hold a load of at least 1800 lbs. This load is concentrated on the five holes that connect the primary I-beam to the ceiling. The primary beams are critical, since if they fail, the entire structure will fail as well and possibly collapse or cause discrepancies in data. Because of the importance of the primary I-beams, it is necessary to know the load that causes the I-beam to fail. A scaled model of the primary I-beam will be used in a tensile testing machine. The I-beam holes are more important than the beam itself since the load will primarily be supported at those locations. To examine the holes, fixing plates have been designed and manufactured. The plates serve to distribute the load in a uniform manner rather than on the entirety of the I-beam. The results of these tests will be very useful to both the DUNE experiment as well as for future LArTPC experiments. [Preview Abstract] |
Saturday, March 24, 2018 11:30AM - 11:42AM |
G3.00006: The Extent and Observable Properties of Nuclear Pasta in Neutron Star Crusts William Newton, Jirina Rikovska Stone, Mark Kaltenborn, Sarah Cantu A layer of nuclear soft condensed matter called nuclear pasta is predicted to mediate the crust-core transition in neutron stars. We present detailed 3D quantum calculations of nuclear pasta in neutron star crusts and proto-neutron stars. We find that nuclear pasta occurs at lower densities than predicted in semi-classical or classical models, and we predict that over 50% of the mass of a neutron star crust is taken up by nuclear pasta independent of uncertainties in the nuclear equation of state. We show that nuclear pasta likely co-exists with spherical nuclei at the lowest densities, and that multiple phases of pasta likely coexist at higher densities. We explore a number of consequences for observables. As a proto-neutron star cools, nuclear pasta tends to keep the outer layers of the star hotter for longer, resulting in an observable imprint on the late-time neutrino signal from supernovae. When the neutron star crust condenses, pasta likely forms microscopic domains characterized by different nuclear geometries, enhancing the disorder of the inner crust and contributing to an observable signal in the cooling of older accreting neutron stars in quiescence. [Preview Abstract] |
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