Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session KC: Instrumentation IV: Dark Matter, Double beta-decay |
Hide Abstracts |
Chair: Krishna Kumar, University of Massachusetts Room: Surf |
Friday, October 26, 2012 2:00PM - 2:12PM |
KC.00001: Measuring fast neutrons with large liquid scintillator for ultra-low background experiments Chao Zhang, Dongming Mei, Keenan Thomas, Patrick Davis, Brian Woltman, Frederic Gray Characterizing neutron background is extremely important to the success of rare event physics research such as neutrinoless double-beta decay and dark matter searches. Measuring the energy spectrum of fast neutrons for an underground laboratory is difficult and it requires intensive R\&D for a given technology. We developed a neutron detector that is constructed using an aluminum tube with one meter in length and 5 inch in diameter filled with 12 liter liquid scintillators. The inner surface of the tube is painted with specular reflector and there are two 5" PMTs (Hamamatsu H4144) attached to both ends. The detector is calibrated with cosmic muons and radioactive sources. Both position independent and position dependent methods are employed to analyze the experimental data. Good neutron/gamma discrimination is found from few MeV to 50MeV above. We report the result for the measurements of fast neutrons on the surface and at underground in Soudan Mine about 1 year data. [Preview Abstract] |
Friday, October 26, 2012 2:12PM - 2:24PM |
KC.00002: Design of Two-Phase Liquid-Xenon Compton-Imaging Detector Christopher Wahl, Ethan Bernard, Christopher Kachulis, Nicole Larsen, Brian Tennyson, Sidney Cahn, Daniel McKinsey, Manawaduge De Silva, Nicholas Destefano, Moshe Gai Liquid xenon offers a unique set of features for gamma and neutron measurements, including high Z, fairly high density (3 g/cm$^{3}$), gamma/neutron discrimination, fast (27-ns) scintillation signals, and demonstrated 4\% FWHM energy resolution at 662 keV. Improvements to an existing detector are being made to create a position-sensitive liquid-xenon detector capable of Compton imaging. The proposed design will operate in two-phase mode to record initial scintillation light (S1), then drift free electrons past sense wires and into a gas region where the electrons will produce proportional scintillation light (S2), which very accurately counts the drifting electrons. The combination of the S1 and S2 signals, which are anti-correlated in energy, is predicted to give 2.6\% FWHM energy resolution at 662 keV. The crossed sense wires will have 3-mm pitch and predicted mm-scale position resolution. A preamp to read out each wire is being designed to fulfill space and noise constraints. In order to precisely know the energy from each gamma-ray interaction, the scintillation light from each interaction must be distinguished from that due to others. Simulation, including optical reflections, is used to determine the optimal optical segmentation of the active volume using thin Teflon walls. [Preview Abstract] |
Friday, October 26, 2012 2:24PM - 2:36PM |
KC.00003: R{\&}D Toward Future Liquid Xe Double Beta Detectors Tim Daniels, Joshua Bonatt, Krishna Kumar, Mark Lodato, Cameron Mackeen, Kelly Malone, Andrea Pocar, David Wright We report on several R{\&}D projects aimed at possible future ton-scale Xe detectors for 0nuBB searches. A liquid Xe cell is being developed to measure material reflectivity for Xe scintillation light in liquid Xe, knowledge of which will be important for detector design and optimization. A vacuum test chamber, equipped with with cryogenic cooling and sources of VUV light, is being commissioned for candidate scintillation detectors. Finally, 136Cs, produced by 136Xe(p,n) at an accelerator, is being pursed as a source of Ba+ ions useful to ongoing R{\&}D toward extraction and identification of the double beta decay daughter in $^{136}$Xe. [Preview Abstract] |
Friday, October 26, 2012 2:36PM - 2:48PM |
KC.00004: Progress on the Characterization of the Yale ``PIXeY'' Two-Phase Xenon Detector Nicholas Destefano, Moshe Gai, Daniel McKinsey, Ethan Bernard, Sidney Cahn, Alessandro Curioni, Blair Edwards, Christopher Kachulis, Nicole Larsen, Alexey Lyashenko, James Nikkel, Yunchang Skin, Christopher Wahl, Alexander Young PIXeY (Particle Identification in Xenon at Yale) is a two-phase (liquid/gas) xenon prototype detector with 3-kg active mass. The two-phase xenon technology has many applications that include gamma-ray imaging, neutrinoless double beta decay searches, and dark matter searches. PIXeY was built to optimize energy resolution and gamma/neutron discrimination, with a number of technological improvements over previous work. Parallel-wire grids, which control the drift and proportional-scintillation fields, are optimized both for light collection efficiency and field uniformity. High quantum efficiency Hamamatsu R8778 PMTs, high-reflectivity Teflon walls, and charge-light anti-correlation techniques are also incorporated. PIXeY will serve as a platform for future improvements, including multiple optical volumes and single wire readout for R{\&}D on gamma-ray imaging and track-imaging studies. The latest progress on the detector will be presented. [Preview Abstract] |
Friday, October 26, 2012 2:48PM - 3:00PM |
KC.00005: Measuring Ionization Efficiency of Germanium Detector Using E0 Transition of 72Ge D'Ann Barker, Dongming Mei, Wenzhao Wei Ionization efficiency plays a crucial role in the interpretation of experimental results for the WIMP-induced dark matter signature. We previously proposed an analytic model that calculates the ionization efficiency for germanium detectors. To test the accuracy of this model, we have measured ionization efficiency of nuclear recoils in germanium by utilizing the characteristic E0 transition of germanium-72 with an AmBe neutron source. Due to the superposition of the internal conversion electrons and nuclear recoils, the signature is a triangular shape, which is well identified from background events. The nuclear recoils are measured down to keV range. We extracted the 692 keV Gaussian distributions of electrons using well-established model from energy calibration. A Monte Carlo simulation is used to determine the energy of nuclear recoils. In this paper, we show the measured ionization efficiency in contrast to the proposed theoretic model for ionization efficiency. All available models and measurements are compared and a reliable model is identified. [Preview Abstract] |
Friday, October 26, 2012 3:00PM - 3:12PM |
KC.00006: Plasma Time in Discriminating Nuclear Recoils in Germanium Detector for Dark Matter Searches Dongming Mei, D'Ann Barker In the detection of WIMP-induced nuclear recoils with high-purity germanium detectors, CDMS-type bolometers are often used in measuring the ionization yield. For this technology, the detector is operated in the milli-Kelvin temperature range, which requires high priced detectors. Alternative electron/nuclear recoil discrimination using pulse shape has been widely utilized in the energy range of MeV in neutrinoless double-beta decay experiments with germanium detectors. However, the nuclear recoils induced by WIMPs are in the energy range of keV, and their pulse shape difference with electronic recoils in the same energy range has not proven to be visible in a commercially available germanium detector. This paper presents a new idea of using plasma time difference in pulse shape to discriminate nuclear recoils from electronic recoils. We show the plasma time difference as a function of nuclear recoil energy. The technique using plasma time will be discussed with a generic germanium detector. [Preview Abstract] |
Friday, October 26, 2012 3:12PM - 3:24PM |
KC.00007: The LZ Dark Matter Experiment Victor M. Gehman One of the most important open questions in physics is the fundamental nature of the dark matter. The direct detection of a dark matter particle in a terrestrial experiment would dramatically impact cosmology and particle physics, and would open a window on a new type of observational astrophysics. The LZ collaboration has proposed to construct a 7-ton liquid xenon dark matter detector at the 4850 level of the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The LZ detector will be based upon the well-established liquid xenon TPC technology, and will capitalize upon the existing infrastructure of the LUX experiment to allow for a rapid turn-around after the conclusion of LUX data taking. With a ducial mass of more than 5 tons, the experiment will probe WIMP-nucleon cross sections down to $2\times 10^{-48}$ cm$^2$ in 3 years of operation. This represents an improvement of approximately 5000 times over current results, covering a substantial range of theoretically-motivated particle dark matter candidates. [Preview Abstract] |
Friday, October 26, 2012 3:24PM - 3:36PM |
KC.00008: Status of the MiniCLEAN Dark Matter Experiment Stanley Seibert The MiniCLEAN dark matter experiment is an ultra-low background single phase liquid argon dark matter experiment that will begin data collection at SNOLAB in 2013. With a fiducial volume of 150 kg, MiniCLEAN will perform a dark matter search and demonstrate several of the technologies and analysis techniques required to build and operate liquid argon and neon detectors at the 100 ton scale for dark matter and solar neutrino experiments. I will discuss the current status of MiniCLEAN construction and component testing, as well as progress on analysis techniques to improve pulse-shape discrimination in argon. [Preview Abstract] |
Friday, October 26, 2012 3:36PM - 3:48PM |
KC.00009: Calibration of a Antineutrino Detector for the Monitoring of a CANDU Reactor Nicholas Walsh, R. Svoboda, A. Bernstein, N. Bowden, T. Classen, B. Cabrera-Palmer, L. Kogler, D. Reyna, G. Jonkmans, B. Sur Detecting antineutrinos emitted from nuclear reactors has been previously demonstrated as a monitor of fuel content and usage. The continuous fuel cycle of a CANDU on-load reactor presents a unique challenge for monitoring. We present the calibration and characterization of a detector designed for this task. The detector will be deployed Fall 2012 at Point Lepreau Generating Station. [Preview Abstract] |
Friday, October 26, 2012 3:48PM - 4:00PM |
KC.00010: Searching for Dark Matter with the CoGeNT and C-4 Detectors Mark Kos Recently published CoGeNT data shows an excess of events at energies below 1.2 keV. The excess at low energies is compatible with light-WIMP nucleon scattering. While it is hard to imagine a background model to explain the spectral and temporal characteristics of the CoGeNT data, a thorough simulation of the external backgrounds is needed to quantify their contribution. In this analysis we simulate both external cavern neutrons and muon induced spallation events inside the CoGeNT shielding. We also model radioactive backgrounds from the shielding materials. The resulting background distributions are compared with the CoGeNT data and we discuss how closely the backgrounds resemble the CoGeNT data. We also discuss plans for the next larger generation of CoGeNT, C4. We will discuss the expected WIMP sensitivity of C4 and contrast to current dark matter experiments. We will also show how we plan to improve upon the CoGeNT design to lower the backgrounds for C4. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700