Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Y14: Detector R&D III |
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Sponsoring Units: DPF Chair: Young-Kee Kim Room: Sheraton Plaza Court 3 |
Tuesday, April 16, 2019 1:30PM - 1:42PM |
Y14.00001: Calculation and Measurement of the Interstrip Capacitance on the Readout Board of the GE2/1 GEM Detector Stephen D Butalla, Marcus Hohlmann The Phase 2 upgrade of the CMS experiment at CERN will increase the luminosity by a factor of ten. In order to cope with the higher muon trigger rates from the increased luminosity, the GE2/1 gas electron multiplier (GEM) detector has been proposed. A critical factor in the design of this detector is the interstrip capacitance of the strips on the readout board (ROB); by decreasing the interstrip capacitance, the noise in the detector can be lowered, which consequently improves the signal-to-noise ratio. This presentation will report on the analytical calculations and measurements of the interstrip capacitance of twelve different configurations of strip dimensions that are proposed for the M1 and M4 modules of the GE2/1 detector. The results of these calculations successfully predict the behavior of the interstrip capacitance of strip designs with different dimensions and geometries. Measurements of the interstrip capacitance were made both with and without an opposing copper plane, which simulates the capacitance due to the third GEM foil in the detector. Additionally, equivalent noise charge (ENC) measurements were made for each sector, and show a linear correlation with the interstrip capacitance. |
Tuesday, April 16, 2019 1:42PM - 1:54PM |
Y14.00002: Wavelength Shifting Liquid-Filled Capillaries for Compact Optical Electromagnetic Calorimetry Applications Randal C Ruchti, Mark Vigneault, Daniel Smith, John Taylor, Kiva Ford
Wavelength Shifting (WLS) Capillaries are being developed for optical calorimetry applications, and particularly for sampling calorimetry configurations. The WLS dyes can be tailored appropriately to provide wave shifting for various scintillation materials. Fabricated from radiation hard quartz, the capillaries are capable of withstanding high radiation doses and could be used broadly for EM applications in fixed target and colliding beam experiments. Our initial focus has been on the optical readout of Shashlik-style modules consisting of alternating layers of dense absorber plates, interspersed with crystal scintillation plates of identical cross sectional area. Such materials afford a dense, compact design, with small Moliere Radius, short physical length and substantial depth in radiation lengths sufficient to contain EM showers. Scintillation light from the crystal tiles is wave shifted in the liquid core of the thick-wall capillaries which penetrate through the Shashlik structure and is then transmitted to photosensors such as SiPM located at their ends. Details of the quartz capillary manufacture, optical characteristics and efficiency and radiation hardness will be presented. |
Tuesday, April 16, 2019 1:54PM - 2:06PM |
Y14.00003: Modeling Magnetic Fields with Helical Solutions to Laplace’s Equation Brian Pollack, Ryan Pellico, Cole Kampa, Henry Glass, Michael Schmitt The series solution to Laplace’s equation in a helical coordinate system is derived and refined using |
Tuesday, April 16, 2019 2:06PM - 2:18PM |
Y14.00004: Spatial Imaging of Charge Transport in Silicon at Low Temperature Chris C Stanford We present direct imaging measurements of charge transport across a 1 cm by 1 cm by 4 mm crystal of high purity silicon (20 kOhm*cm) at temperatures between 500 mK and 5 K. We use these data to determine the intervalley scattering rate of electrons as a function of the electric field applied along the [111] crystal axis, and we present a phenomenological model of intervalley scattering that explains the constant scattering rate seen at low-voltage for cryogenic temperatures. We also present a measurement of the collection efficiency for drifting electrons and holes in Si as a function of temperature from 300 K down to 1 K, from which we have gained insight into low-temperature phonon physics, charge trapping, and impact ionization. |
Tuesday, April 16, 2019 2:18PM - 2:30PM |
Y14.00005: Ultrastrong coupling of CdZnS/ZnS quantum dots and breathing plasmons in Aluminum metal-insulator-metal nanocavities in near-ultraviolet spectrum Li Li Abstract: Strong coupling between excitons of quantum dots and plasmons in nanocavites can be realized at room temperature due to the strong confinement of the plasmon fields, which offers building blocks for quantum information systems or ultralow-power switches and lasers. However, most of previous strong coupling effect were realized by the interaction between exctions and bright plasmon modes in visible range. In this work, by using cathodoluminescence, ultrastrong coupling with Rabi splitting above 1 eV between breathing plasmons in Aluminum metal-insulator-metal (MIM) cavity and excited state of CdZnS/ZnS quantum dots was reported in near-UV spectrum. Analytic analysis and full-wave electromagnetic simulations provide the evidence for the strong coupling and confirm the hybridization of the QDs exciton and LSP breathing mode. This study opens the way for new emerging applications based on strongly coupled light-matter states all over the visible region down to ultra-violet frequencies.
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Tuesday, April 16, 2019 2:30PM - 2:42PM |
Y14.00006: Hot-Electron Plasmonics for Ultrafast Control of Intensity, Phase, and Polarization of light Mohammad Taghinejad, Wenshan Cai The term “hot electron” is often used in the literature to describe electrons in a solid with energies exceeding their thermally-created counterparts at room temperature. In plasmonic structures, the nonradiative dephasing of plasmons generates excited (i.e., athermal) electrons in the conduction band of metals and a subsequent electron thermalization step leads to the equilibration of athermal electrons and the formation of a hot-electron distribution. Exploring the dynamics of such energetic electrons has recently gained a growing attention with the hope for the implementation of active plasmonic platforms. Here, we show that the ultrafast transfer of hot electrons from plasmonic metals to dielectric materials allows for the suppicosecond (< 190 fs) modulation of plasmonic responses. Our findings suggest that the activation of hot-electron transfer pathways lower the impact of electron-photon interactions and instead provide an electron-dominated relaxation mechanism. Through the design of a subradiant, high-Q, and polarization-sensitive plasmonic crystal we demonstrate ultrafast control of phase, polarization, and intensity of light in an all-optical manner. 1. Taghinejad et al, Advanced Materials 30, 17049015-21 (2018) 2. Taghinejad et al, Nano Letters 18, 5544-5551 (2018) |
Tuesday, April 16, 2019 2:42PM - 2:54PM |
Y14.00007: Nuclear recoil calibration of SuperCDMS HVeV detectors using a neutron scattering setup Runze Ren The SuperCDMS experiment has been developing silicon and germanium detectors optimized for phonon signals from dark matter-nucleus collisions. The detectors are sensitive to dark matter masses between about 1 and 10 GeV/c^2, which corresponds to sub-keV energy deposits from the nuclear recoil signal. The sensitivity of a SuperCDMS HVeV detector is achieved by applying a high voltage across the crystal. Under the electric field, the signal from electron-hole pairs generated from nuclear recoil events is amplified through the Neganov-Trofimov-Luke (NTL) effect. However, the yield of electron-hole pairs, which is critical to reconstructing the energy of the recoiling nucleus, is not well characterized in the sub-keV nuclear recoil energy region. I will describe a neutron scattering experiment designed to measure the ionization yield in SuperCDMS style detectors. |
Tuesday, April 16, 2019 2:54PM - 3:06PM |
Y14.00008: Measurement of neutron activation of tritium in silicon using CCDs. Ryan J Thomas A major source of background in next-generation silicon-based dark matter experiments (such as DAMIC or SuperCDMS) is cosmogenic activation of tritium in the silicon detector material. Tritium is relatively long lived (compared to the time scale of dark matter experiments) and decays through a low energy beta decay, creating a significant irreducible background for silicon-based searches of low mass WIMPs or other low energy dark matter candidates. The cosmogenic activation rate of tritium in silicon is currently poorly understood, due the difficulties in measuring natural cosmogenic tritium contamination. An alternative method is to expose silicon to a high intensity neutron beam with a known spectrum similar to the natural cosmogenic spectrum and extrapolating the natural cosmogenic tritium activation rate from this much higher neutron exposure. We present results of exposing a silicon charge-coupled device (CCD) to the LANSCE neutron beam at Los Alamos and measuring the resulting tritium using the CCD directly. |
Tuesday, April 16, 2019 3:06PM - 3:18PM |
Y14.00009: Impact Ionization in SuperCDMS HVeV Detectors Francisco Ponce, Paul Brink, Blas Cabrera, Matthew A. Cherry, Caleb Fink, Noah Kurinsky, William Page, Richard Allan Partridge, Matt Pyle, Bernard Sadoulet, Bruno Christian Serfass, Chris C Stanford, Samuel Watkins, Steven J. Yellin, Betty Young The existence of Dark Matter (DM) is supported by astronomical data and observations; however, to date there is no confirmed direct detection of DM. The SuperCDMS collaboration has expanded its capabilities with the development of the prototype HVeV detector. The HVeV detector uses a high voltage applied across the Si (or Ge) crystal to accelerate charges, which scatter off the crystal lattice generating additional phonons via the Neganov-Trofimov-Luke (NTL) effect. The total energy of the generated phonons is equal to the number of e-h+ pairs times the applied voltage, thus the detector response is quantized from the discrete e-h+ pair production. Unfortunately, the accelerated charges can (with some probability) free other loosely bound charges throughout the crystal, referred to as impact ionization. The observed energy from events that undergo impact ionization will not be quantized due to an incomplete NTL effect on the freed charges. These types of events will lie between the quantized peaks and appear as a flat high energy background. Here we discuss a technique for studying the effect of impact ionization on the SuperCDMS HVeV detector using a pulsed laser at ultra-low intensity. |
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