Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session Y8: Novel Instrumentation |
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Sponsoring Units: DPF Chair: David Saltzberg, University of California, Los Angeles Room: Grand F |
Tuesday, May 3, 2011 1:30PM - 1:42PM |
Y8.00001: Shielding Photomultiplier Tubes from Magnetic Fields at Cryogenic Temperatures: Results from MicroBooNE Testing Timothy McDonald, Thomas Briese, Paul Nienaber Photomultiplier tube [PMT] performance can be affected by ambient magnetic fields, even ones as small as the Earth's. Large diameter tubes (eight inches or greater), such as those used in neutrino detectors, are no exception; the cryogenic environment in the MicroBooNE detector (which houses a Liquid Argon Time Projection Chamber [LArTPC] and will use eight-inch PMTs for scintillation light detection) poses an additional challenge. This report details the use of a test stand to rotate PMTs inside a vessel that can be filled with liquid nitrogen or argon, and the performance of tubes shielded with materials designed for use at cryogenic temperatures. [Preview Abstract] |
Tuesday, May 3, 2011 1:42PM - 1:54PM |
Y8.00002: Boron and thermal neutron interactions on borosilica window photomultiplier tubes Ugur Akgun The borosilica, a very common PMT window and envelope material, contains 5{\%} Boron (1{\%} $^{10}$B). The high cross section for $^{10}$B capturing thermal neutrons (3980 barn), is a concern for LHC experiments using borosilica window PMTs. This study investigates the rate and the size of the signals generated by thermal neutron boron interaction in borosilica window PMTs; Hamamatsu R7525-HA and R7600U-200-M4. Although virtually all of the thermal neutrons incident on the borosilicate glass are absorbed, probability of generating a PMT signal was measured to be 3$\times $10$^{-4}$ and 3$\times $10$^{-6}$ for R7525-HA and R7600U-200-M4 PMTs, respectively. For these signals the average pulse size was found to be between 20--30 photoelectrons. We also discuss that four anode PMTs allow the elimination of these events with an of?ine algorithm. [Preview Abstract] |
Tuesday, May 3, 2011 1:54PM - 2:06PM |
Y8.00003: Study of New Anisotropic Conductive Adhesive for Bump Bonding Richard Lander, Robert Fields, Angela Galvez, Britt Holbrook, Benjamin Michlin, Alexandra Moskeleva, Christian Neher, Mani Tripathi, Michael Woods Anisotropic Conductive Adhesives (ACF) used in flip chip bump bonding allow for several pairs of aligned metal pads to be connected without placement of individual metal bumps on each pad. Typical ACFs use small spheres distributed in a bonding film. A new type of ACF described here uses vertically aligned nickel needles imbedded in thermoplastic film to make the connections. We have been investigating the suitability of this ACF for certain work in bonding chips for high energy physics detectors. Resistance of the bond has been measured under various conditions of bonding pressure, temperature, and pad size. Milliohm values of resistance have been obtained for certain condition. Procedures and results will be discussed [Preview Abstract] |
Tuesday, May 3, 2011 2:06PM - 2:18PM |
Y8.00004: Beam Tests of Directly Coupled Scintillator Tiles and Silicon Photomultipliers Stephen Cole, Gerald Blazey Scintillator tiles directly coupled to photo-sensors (without wavelength shifting fiber) offer greatly simplified construction for highly granular detectors. The performance of these detectors requires uniform response across the surface of the scintillator. Flat and shaped scintillator tiles directly coupled to silicon photo-multipliers have been investigated with both a radioactive source and high energy protons. We present results which indicate that, as expected, flat cells have high response near the photo-sensors while shaped cells have a much more uniform response, suggesting cells can be tailored to ensure uniform response. We also present results demonstrating that the response of the cells to a source and to beam particles are in qualitative agreement. [Preview Abstract] |
Tuesday, May 3, 2011 2:18PM - 2:30PM |
Y8.00005: Design of the Next Generation SuperCDMS Detectors Scott Hertel While the the SuperCDMS collaboration deploys the first of its new ``interleaved'' (iZIP) detectors underground at the Soudan Mine, a concurrent effort is under way to design and test the next generation of detectors for a larger experiment at SNOLab. The detector design effort is focused on using larger 100mm diameter Ge crystals to increase the overall target mass to $\sim$100kg while retaining or even improving background rejection. We will discuss the current status of this effort, emphasizing fundamental design strategies and the results of relevant Monte Carlo simulations. [Preview Abstract] |
Tuesday, May 3, 2011 2:30PM - 2:42PM |
Y8.00006: Goals and Status of MICE, the International Muon Ionization Cooling Experiment Pavel Snopok Muon ionization cooling provides the only practical solution to preparing the low-emittance muon beams suitable for a neutrino factory or a muon collider. The Muon Ionization Cooling Experiment (MICE) thus represents a strategic R\&D project for neutrino physics. MICE is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated muon beam line able to generate a range of input emittance and momentum values, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. A first measurement of emittance will be performed in the upstream magnetic spectrometer with a scintillating-fiber tracker. A cooling cell will then follow, alternating energy loss in liquid-hydrogen absorbers and RF acceleration. A second spectrometer, identical to the first, and a second muon identification system provide a measurement of the outgoing emittance. In the 2010 run, completed in August, the beam and most detectors were fully commissioned. Results from this run will be presented. The plan for measurements of emittance and emittance reduction (cooling) that will follow in 2011 and beyond will also be reported. [Preview Abstract] |
Tuesday, May 3, 2011 2:42PM - 2:54PM |
Y8.00007: Status of the EXO gas detector R{\&}D Kirill Pushkin The EXO collaboration is searching for neutrinoless double beta decay using 80{\%} isotopically enriched Xenon ($^{136}$Xe). A 200 kg liquid phase detector running currently at WIPP is expected to reach a Majorana neutrino mass sensitivity of $\sim $135 meV. EXO is also conducting R{\&}D toward a high pressure xenon gas detector using enriched $^{136}$Xe at up to 10 bar of pressure. This technique might offer better energy resolution than a liquid Xenon detector and allow discrimination between single and double electrons thus suppressing detector background. The high pressure xenon detector would utilize scintillation light to attain high energy resolution. Achieving good energy resolution requires very low concentration of electronegative impurities in the gas and, in turn, reliable and robust purification techniques. Detection of Ba$^{++}$ ions, not possible in liquid xenon, may be possible in the gaseous phase. Ba$^{++}$ ions could be transported by high electric fields in the gas to a nozzle where they can be subsequently extracted and detected in order to separate signal events from radioactive background. The status of the detector design, construction, Ba$^{++}$ identification, gas handling system, purification, and vacuum-sampling system will be presented. [Preview Abstract] |
Tuesday, May 3, 2011 2:54PM - 3:06PM |
Y8.00008: Xenon purity measurements via mass spectroscopy for the EXO-200 double beta decay experiment Yung-Ruey Yen We report on the construction and operation of a gas sampling and measurement system for the EXO-200 double beta decay experiment. In order to observe ionization charge and scintillation light from the double beta decay event, EXO requires the concentration of electronegative impurities such as oxygen to be less than one part per billion. We have constructed a dedicated gas sampling and measurement apparatus to monitor for the presence of these impurities and to determine their source. Half-liter samples of xenon gas are collected at various points in the EXO-200 gas handling system, and their composition is analyzed using a RGA mass spectrometer. In order to achieve the required sensitivity, the apparatus includes a cold trap which removes most of the bulk xenon from the sample before it reaches the RGA. This system has allowed us to certify the purity of the commercial xenon source cylinders before detector filling and to monitor the effectiveness of the gas purifiers. [Preview Abstract] |
Tuesday, May 3, 2011 3:06PM - 3:18PM |
Y8.00009: The EXO-200 Liquid Xenon Time Projection Chamber Simon Slutsky The Enriched Xenon Observatory (EXO) is an experimental program to search for neutrinoless double beta decay in 136Xe. The first EXO experiment, EXO-200, consists of a time projection chamber (TPC) filled with 200 kg of liquid xenon. In this way, the xenon is both the source and the ionized/scintillating medium needed for the TPC. The detector is installed 2250 feet underground at the WIPP facility in Carlsbad, NM, and is currently taking data. I will discuss the design and operation of the detector. [Preview Abstract] |
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