Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session G13: Instrumentation for Dark Matter Detection |
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Sponsoring Units: DAP DPF GPMFC Chair: Juan Collar, University of Chicago Room: Royal EF |
Sunday, May 1, 2011 8:30AM - 8:42AM |
G13.00001: Proportional scintillation light signal in the XENON100 - optimization and characterization Emilija Pantic The ionization detection channel in the XENON100 detector is measured via secondary scintillation light (S2 signal) that is proportional to the amount of charge produced by a particle interaction. The S2 signal is determined both by the reduced field (field/pressure), which induces electroluminescence by accelerating extracted electrons from the liquid, and the electron drift length within the gas gap. In this talk we report on the charge response of the XENON100 detector. The S2 signal optimization includes leveling of the detector to achieve uniformity of the signal and tuning of the liquid level to obtain an optimal S2 signal response. The S2 signal characterization is performed using different calibration sources to measure its yield, resolution, position and time dependence. Detection of single electrons with the XENON100 detector enables excellent sensitivity to detection of low mass WIMPs. [Preview Abstract] |
Sunday, May 1, 2011 8:42AM - 8:54AM |
G13.00002: The Photomultiplier Calibration Procedure for the DarkSide Dark Matter Program Jason Brodsky The charge calibration of the photomultiplier tubes in the DarkSide-10 dark matter detector prototype is carried out by measuring their response to small numbers of photoelectrons induced by a pulsed laser. This calibration requires fitting the observed charge spectrum to a function that accurately describes the behavior of the photomultiplier tube. Based on previous external work, I have developed a fitting function that is robust against a class of non-ideal photomultiplier responses. This fitting function improves on the previous work by fully accommodating ``pedestal'' noise, reducing the need to introduce potentially biasing noise-reduction measures. [Preview Abstract] |
Sunday, May 1, 2011 8:54AM - 9:06AM |
G13.00003: Systematic Characterization of the QUPID Photodetector Kevin Lung The discovery potential of future direct detection dark matter experiments relies heavily upon achieving a background-free environment in the sensitive volume. Current generation noble liquid detectors are limited by the radioactivity of the external materials, mostly from the photomultiplier tubes. A collaborative effort between UCLA and Hamamatsu has resulted in the development of a low radioactive Quartz Photon Intensifying Detector (QUPID) based upon hybrid APD technology. In the UCLA photosensor testing facility, characterizations of both the QUPID and a 3-inch conventional Hamamatsu R11065 photomultiplier tube have been made using identical systems. The properties examined include the single photoelectron gain, gain versus high voltage, linearity, uniformity, and dark count rate. This talk demonstrates the results of tests performed on the QUPID and R11065. [Preview Abstract] |
Sunday, May 1, 2011 9:06AM - 9:18AM |
G13.00004: Charge Transport Studies in SuperCDMS Detectors Arran Phipps, Kyle Sundqvist, Albert Lam, Bernard Sadoulet We present an overview of charge transport in CDMS (Cryogenic Dark Matter Search) germanium detectors. Complete charge collection is necessary to correctly distinguish between electron and nuclear recoils, however carrier transport under the CDMS operating regime of low temperature ($\sim$40mK) and low field ($\sim$V/cm) is poorly understood. We discuss our current understanding of carrier dynamics and how this translates into the observed detector response. Our theory is compared to direct measurements of transport properties we performed on SuperCDMS detectors. [Preview Abstract] |
Sunday, May 1, 2011 9:18AM - 9:30AM |
G13.00005: Measurement of the reflectivity to 178nm light of the PTFE used in the Xenon100 Bin Choi The XENON100 time projection chamber (TPC) uses polytetrafluoroethylene (PTFE) both as insulator and as VUV-light reflector. The reflectivity of PTFE, however, is not well established, especially considering that it significantly depends on the surface finish. Furthermore, the PTFE in XENON100 is in contact with the liquid xenon at about -100$^{\circ}$C, which can also affect the reflecting property. A set-up consisting of a monochromator and a vacuum chamber was developed within the XENON100 collaboration and operated at the Columbia University Nevis Laboratory to measure the reflectivity of PTFE and other material samples, relevant for future XENON detectors. The chamber is equipped with an Iwatani PDC08 pulse tube refrigerator (PTR) to be able to cool down the samples to liquid xenon temperature. The same set-up has also been used to measure, for the first time, the quantum efficiency (QE) of the Hamamatsu R8520-06-AL XENON100 photomultipliers at low temperature. [Preview Abstract] |
Sunday, May 1, 2011 9:30AM - 9:42AM |
G13.00006: Update of Direct Dark Matter Search using CCDs Natalie Harrison, Juan Estrada There is currently vast evidence for Dark Matter (DM) from astronomical observations. However, in spite of tremendous efforts by large experimental groups, there is no confirmed direct detection of the dark matter in our galaxy. Recent experimental results and theoretical developments suggest the possibility of a DM particle with mass below 10 GeV, such a particle would escape most of the direct searches due to the large thresholds for the detection of nuclear recoils typically used. In this work we study the possibility of a new Dark Matter search with an unprecedented low threshold for the detection of nuclear recoils using high-resistivity CCD detectors (hr-CCD). Due their extremely low readout noise and the relatively large active mass, these detectors present a unique opportunity in this field. [Preview Abstract] |
Sunday, May 1, 2011 9:42AM - 9:54AM |
G13.00007: Simulations of TES Sensors for SuperCDMS Adam Anderson, Steven Leman, Kevin McCarthy, Enectali Figueroa-Feliciano The Cyrogenic Dark Matter Search (CDMS) instruments germanium crystals with transition-edge sensors (TES) in order to detect phonons produced by nuclear recoils. Phonons are converted into quasiparticle excitations that diffuse into a voltage-biased array of TES wired in parallel. A simulation of the CDMS TES array, including superconducting-normal resistance phase separation, is described. We also discuss measurements to characterize the sensors, which allow us to tune simulation parameters such as the critical temperature and its spatial variation, parasitic resistance, thermal diffusivity, and thermal coupling of the electron and phonon systems. The results of the tuned simulation require phase separation and are compared with test data from the CDMS detectors. [Preview Abstract] |
Sunday, May 1, 2011 9:54AM - 10:06AM |
G13.00008: New Measurement of the Scintillation Efficiency of Low Energy Nuclear Recoils in Liquid Xenon Guillaume Plante, E. Aprile, R. Budnik, B. Choi, K.-L. Giboni, R.F. Lang, K.E. Lim, A.J. Melgarejo Fernandez The uncertainty in the relative scintillation efficiency of nuclear recoils, $\mathcal{L}_{\mathrm{eff}}$, at low energies is the largest systematic uncertainty in the reported results from liquid xenon (LXe) WIMP searches at low masses (\textless 15 GeV). A new single phase LXe detector has been designed and built specifically for the measurement of $\mathcal{L}_{\mathrm{eff}}$ at low energies. For the design of the detector, the emphasis has been placed on the maximization of the scintillation light detection efficiency to obtain the lowest possible energy threshold. We present the results of a new measurement of $\mathcal{L}_{\mathrm{eff}}$ at low energies performed with this detector by recording fixed-angle elastic scatters of 2.5 MeV monoenergetic neutrons from a deuterium-deuterium neutron generator. [Preview Abstract] |
Sunday, May 1, 2011 10:06AM - 10:18AM |
G13.00009: Characterization of QUPID Photodectors Under Liquid Xenon Artin Teymourian The sensitivity of the current generation of Noble Liquid Dark Matter detectors is limited by background events originating from radioactivity in the detector materials. A major source of this radioactivity is the Photomultiplier Tubes used to detect scintillation light from the noble liquid. In this talk, I will present a novel concept for a new style of photodetector based on the design of Hybrid APDs. The Quartz Photon Intensifying Detector (QUPID) is made nearly entirely out of radiopure quartz, thereby decreasing the radioactivity by at least an order of magnitude over conventional phototubes. The Hybrid APD design, which focuses accelerated electrons onto an APD, also allows for very high linearity. By using QUPIDs, future noble liquid detectors will have drastically lower background levels, corresponding to much better sensitivities for dark matter detection. I will discuss the development and testing of the QUPID, specifically operation of the QUPID under Liquid Xenon and the detection of scintillation light from the xenon. [Preview Abstract] |
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