Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session T14: Detectors and Upgrades IIILive
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Sponsoring Units: DPF Chair: Roger Rusack, University of Minnesota Room: Virginia A |
Monday, April 20, 2020 3:30PM - 3:42PM Live |
T14.00001: Experimental study of electrical conduction mechanisms in P-type amorphous germanium (Ge) used as contacts for Ge detectors in search for rare-event physics Sanjay Bhattarai, Rajendra Panth, Dongming Mei, Jing liu, wenzhao wei The surface leakage current of a High purity Germanium detector can decrease the detector performance significantly. This surface leakage current mainly depends upon the electrical property of the passivating material(a-Ge).Electrical conduction mechanisms in the disordered material system p-type amorphous germanium (a-Ge) used for surface passivation of a high purity germanium detector were experimentally studied for the first time. The localization length and the Hopping parameters in a-Ge were determined using the surface leakage current measured from three high-purity planar germanium detectors. The temperature-dependent hopping distance and hopping energy were obtained for a-Ge fabricated as the electrical contact materials for high-purity germanium planar detectors. As a result, we find that the hopping energy in a-Ge increases as temperature increases while the hopping distance in a-Ge decreases as temperature increases. The localization length of a-Ge is on the order of 1.7 A$^{\mathrm{o}}$ to 2.94 A$^{\mathrm{o}}$, depending on the density of states near the Fermi level. [Preview Abstract] |
Monday, April 20, 2020 3:42PM - 3:54PM Live |
T14.00002: Study of effective segregation coefficient of impurities in HPGe for developing Ge detectors in searching for rare-event physics Pramod Acharya, Sanjay Bhattarai, Mathbar Raut, Hao Mei, Dongming Mei Developing large-size high-purity Germanium (HPGe) detectors is necessary for detecting rare-event physics. Fabricating large-size HPGe detectors requires to grow large-size HPGe crystals, which is strongly coupled to the control impurity segregation in the growth process. We study the effective segregation coefficient of impurities Al, B, Ga and P in HPGe identified through PTIS method in a crystal grown by Czochralski technique. Hall effect measurement was used to determine the impurities concentration profile in HPGe. The average value of effective segregation coefficient, K$_{\mathrm{eff}}$, for B, Al, Ga, and P was obtained to be 9.45, 0.70, 0.29, and 0.18 respectively using normal segregation equation. The thickness of the critical boundary layer at which the segregation occurring was analyzed for each of these impurities in a BPS model. The results were compared with the physical model. This study allows us to better control the crystal growth process in growing large-size crystals for developing HPGe detectors. [Preview Abstract] |
Monday, April 20, 2020 3:54PM - 4:06PM Live |
T14.00003: Tracker Electronics in Mu2e Andrea Herman The Mu2e experiment is a future search for charged lepton flavor violation through the conversion of a muon to an electron in the field of a nucleus. The experiment will use a straw tube tracker to reconstruct the momentum of electrons, which provide the primary signal. Here I present the electronics which will be utilized by the tracker and our ongoing work for testing and quality assurance. [Preview Abstract] |
Monday, April 20, 2020 4:06PM - 4:18PM On Demand |
T14.00004: HP-Ge Crystal Growth at USD for Developing Ge detectors in Searching for Rare-Event Physics Hao Mei, Sanjay Bhattarai, Mathbar Raut, Pramod Acharya, Dongming Mei Detector grade High-Purity Germanium(HP-Ge) crystals are largely needed for rare event physics. At the University of South Dakota (USD), we have successfully built a production chain that can purify the commercially available Ge raw materials, grow detector-grade HP-Ge crystals, and fabricated them into Ge detectors. Zone refining and crystal growth are the two important steps to obtain HP-Ge crystals. A well-controlled segregation method is used to control the distribution of impurities during crystal growth. A summary of our current progress and inventory of detector grade crystals, including all the USD detectors made by USD crystals will be reported. [Preview Abstract] |
Monday, April 20, 2020 4:18PM - 4:30PM On Demand |
T14.00005: Development of HPGe detectors with amorphous Ge contacts for rare-event physics searches Wenzhao Wei, Rajendra Panth, Xianghua Meng, Hao Mei, Guojian Wang, Dongming Mei, Jing Liu Large high-purity germanium (HPGe) detectors are needed for dark matter and neutrinoless double-beta decay experiments. Currently, large (up to 10 cm in diameter) HPGe crystals with impurity concentration below 5*10$^{\mathrm{10}}$/cm$^{\mathrm{3\thinspace }}$can be grown at the University of South Dakota (USD). The quality of USD-grown crystals has been verified to be sufficient for use in large detectors by converting those crystals into small planar HPGe detectors and characterizing the detector performance. We report the testing results from ten good detectors fabricated so far with amorphous germanium (a-Ge) contacts, which can block both electrons and holes. We investigated an important property of the a-Ge contacts, the energy barrier to charge injection, to optimize the a-Ge contacts and thus minimize the detector leakage current. We also studied the charge trapping processes utilizing nine of our planar detectors to have a better understanding of the crystals we grow at USD. [Preview Abstract] |
Monday, April 20, 2020 4:30PM - 4:42PM |
T14.00006: A Novel High Rate Readout System for a High Efficiency Cosmic Ray Veto for the Mu2e Experiment Sten Hansen The Mu2e Cosmic Ray Veto must veto cosmic-ray muons over an area of 335\,m$^2$ with an overall efficiency of about 99.99\% in the presence of high background rates from beam-induced neutrons and gammas. It consists of 5,376 rectangular scintillator extrusions up to 7\,m long with embedded 1.4\,mm wavelength-shifting fibers coupled to $2{\times}2$\,mm$^2$ silicon photomultiplier (SiPM) diodes. A custom readout system has been designed and prototypes have been built and tested. It consists of: (1) small circuit board, the Counter Mother Board, situated on the ends of the scintillator counters, which provides a bias distribution network, a temperature sensor, flasher LEDs, and passive SiPM pulse shaping; (2) a Front End Board which digitizes, zero-suppresses, and stores in on-board memory signals from up to 64 Counter Mother Boards, provides bias to the SiPMs, pulses to the LEDs, and a measurement of the SiPM currents; and (3) a Readout Controller which collects data from the Front End Boards via Category 6 Ethernet cables, which also deliver 48V power to the Front End Boards using the power over Ethernet standard. The data collected in the controllers is formatted appropriately and transmitted over 3.125\,Gb/s optical fibers to the trigger and data acquisition system [Preview Abstract] |
Monday, April 20, 2020 4:42PM - 4:54PM |
T14.00007: A Fast Simulation of Scintillation Counters with Embedded Wavelength-Shifting Fibers Read out by Silicon Photomultipliers Ralf Ehrlich We describe a complete end-to-end simulation of the response of long scintillator counters with embedded wavelength-shifting fibers to charged particles and compare it to test-beam data. The counters were co-extruded with a titanium dioxide surface coating and two channels for the embedded wavelength-shifting fibers. The light is read out by silicon photomultipliers. The simulation includes the production and propagation of scintillation and Cerenkov photons, the response of the silicon photomultipliers, and the generation of the signal waveforms. Lookup tables are used to speed up the simulation of the photon propagation inside the counters. The simulation was tuned to match measured data obtained from a test-beam study in the Fermilab Meson Test Beam Facility using 120 GeV protons. The counters are to be used in the cosmic-ray veto detector for the Mu2e experiment at Fermilab. [Preview Abstract] |
Monday, April 20, 2020 4:54PM - 5:06PM On Demand |
T14.00008: A High Efficiency Cosmic Ray Veto Detector for the Mu2e Experiment at Fermilab E. Craig Dukes The Mu2e experiment is designed to search for the charged-lepton-flavor-violating process, $\mu^-$ to a $e^-$, with unprecedented sensitivity. The single 105-MeV electron that results from this process can be mimicked by electrons produced by cosmic-ray muons traversing the detector. An active veto detector surrounding the apparatus is used to detect incoming cosmic-ray muons. To reduce the backgrounds to the required level it must have an efficiency of about 99.99\% as well as excellent hermeticity. The detector consists of four layers of scintillator counters, each with two embedded wavelength-shifting fibers, whose light is detected by silicon photomultipliers. The design and expected performance of the cosmic ray veto detector will be described. [Preview Abstract] |
Monday, April 20, 2020 5:06PM - 5:18PM |
T14.00009: The CHANDLER Detector Upgrade Tulasi Subedi The MiniCHANDLER detector was deployed in a nuclear power plant that detected an antineutrino signal. We envisioned some improvements that will increase the efficiency of the detector. The current electronics has multiple issues like cross-talk, baseline oscillation after a pulse, limited dynamic range, etc. This talk will describe a custom readout electronics, based on FPGA, optimized for the CHANDLER detector that will eliminate all the issues of the current electronics. In addition, we will discuss the improvements in neutron detection efficiency. [Preview Abstract] |
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