Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session Y10: Nuclear Instrumentation |
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Sponsoring Units: DNP Chair: E. Beise, University of Maryland Room: Maryland B |
Tuesday, February 16, 2010 1:30PM - 1:42PM |
Y10.00001: Development of a segmented fast neutron spectrometer based on $^{6}$Li-loaded liquid scintillator for measuring neutron background Christopher Bass, Craig Heimbach, Jeff Nico, Elizabeth Beise, Herbert Breuer, Dylan Erwin, Tom Langford Fast neutrons induced by natural radioactivity and cosmic rays are important sources of background for low-background experiments such as direct detection of dark matter, neutrinoless double beta decay, and solar neutrinos. One technique for measuring neutron flux employs a delayed coincidence between recoil protons and thermal capture in a liquid scintillator loaded with $^{6}$Li, which ensures that the fast neutron energy is fully absorbed in the scintillator. Fast neutrons are efficiently thermalized in the liquid scintillator, and the recoil protons provide energy information of the incident neutron. The subsequent neutron capture on $^{6}$Li provides a clean unambiguous signal at 530 keV$_{ee}$ that the incident particle was a neutron rather than a background event. Good energy resolution is achieved by compensating the nonlinear light yield of the scintillator with optically segmented sections, which minimize the number of multiple recoil protons per scintillator element. We discuss characteristics and development of a segmented detector, including calibration and associated analysis tools. [Preview Abstract] |
Tuesday, February 16, 2010 1:42PM - 1:54PM |
Y10.00002: A Fast Neutron Spectrometer for Underground Science Thomas Langford, Elizabeth Beise, Herbert Breuer, Dylan Erwin, Christopher Bass, Craig Heimbach, Jeff Nico The characterization of the fast neutron fluence has become a critical issue for experiments that require extreme low-background environments, such as neutrino-less double-beta decay, dark matter searches, and solar neutrino experiments. In such experiments, fast neutrons may be the dominant and a potentially irreducible background, thus necessitating precise information about the fast neutron fluence and energy spectrum. The most reasonable approach to addressing the problem is through the complete characterization of the neutrons through both site-specific measurement and benchmarking of simulation codes. We will discuss the progress toward the development of a large-volume, segmented detector consisting of plastic scintillator and $^3He$ proportional counters. The detector will be placed in an underground environment to measure the fast neutron flux and energy spectrum. A prototype detector has been constructed and testing is in progress. We will discuss the status of the project and present data from the prototype detector. [Preview Abstract] |
Tuesday, February 16, 2010 1:54PM - 2:06PM |
Y10.00003: Sample Preparation and Gamma-Assay Measurements at the Low-Background Counting Facility at the Kimballton Underground Research Facility Jacqueline Strain, Padraic Finnerty, Graham Giovanetti, Reyco Henning, Alex Long, Sean MacMullin, Kevin Macon, John Wilkerson, Henning Back, Richard Lindstrom, Steven Derek Rountree, Bruce Vogelaar The KURF (Kimballton Underground Research Facility) is home to a gamma counting facility, consisting of two HPGe (high purity germanium) detectors specifically designed for low background assay work. We will discuss the techniques and sample preparation done for gamma-assay at this facility. Specifically we will discuss the gamma-assay measurements done for Axon PicoCoax cable which is a possible candidate for the M\textsc{AJORANA} D\textsc{EMONSTRATOR}. We will also discuss the gamma-assay measurements for lead bricks from Sullivan lead that are to be used for shielding in MALBEK (The M\textsc{AJORANA} Low Background BEGe Detector at KURF) and the proposed M\textsc{AJORANA} experiment. [Preview Abstract] |
Tuesday, February 16, 2010 2:06PM - 2:18PM |
Y10.00004: Astroparticle and Nuclear Physics with a Customized Low-Background Broad Energy Germanium Detector Padraic Finnerty As a part of the R\&D process for the M\textsc{ajorana} and CoGeNT experiments, we have found that customized commercial Broad Energy Ge detectors (BEGe) produced by Canberra have several promising features, including large mass, low electronic noise, and excellent pulse-shape analysis capabilities. BEGe detectors obtain these capabilities due to their low-capacitance ``point-contact" style configuration. BEGes are also the only point-contact design fabricated on a commercial basis. We have deployed a customized BEGe, named ``MALBEK" in a low background cryostat in the Kimballton Underground Research Facility in Virginia. This talk will focus on the shield design, detector characteristics, and measurements that can be performed with such a detector in a low-background environment. [Preview Abstract] |
Tuesday, February 16, 2010 2:18PM - 2:30PM |
Y10.00005: Dark Optical Traps for $\beta$-Decay Studies Guy Ron Magneto-Optical Traps (MOTs) have for many years been the workhorse of $\beta$ decay studies using trapped radioactive atoms. These MOTs allow to study the $\beta$ decay of atoms at extremely low temperatures and high vacuum, allowing for a precise extraction of the $\beta$ decay correlation coefficients. MOTs, however, are unsuited for measurements of polarization correlation coefficients since they do not allow the trapped atoms to be easily polarized. Furthermore, the high photon scattering rate in a MOT may introduce population dependent corrections, such as, for example, from molecular dimer production. The LBL atom trapping group is developing two new optically dark traps, based on work done by Davidson {\it et al.}, in which the trapped sample will be confined to a dark region bounded by blue detuned laser light. The concept and status of these traps will be presented and the benefits of using such a trap will be discussed. [Preview Abstract] |
Tuesday, February 16, 2010 2:30PM - 2:42PM |
Y10.00006: A Novel Particle Detector: Quantum Dot Doped Liquid Scintillator Lindley Winslow, Janet Conrad, Ruel Jerry Quantum dots are semiconducting nanocrystals. When excited by light shorter then their characteristic wavelength, they re-emit in a narrow band around this wavelength. The size of the quantum is proportional to the characteristic wavelength so they can be tuned for many applications. CdS quantum dots are made in wavelengths from 360nm to 460nm, a perfect range for the sensitivity of photo-multiplier tubes. The synthesis of quantum dots automatically leaves them in toluene, a good organic scintillator and Cd is a particularly interesting material as it has one of the highest thermal neutron cross sections and has several neutrinoless double beta decay and double electron capture isotopes. The performance of quantum dot loaded scintillator compared to standard scintillators is measured and some unique properties presented. [Preview Abstract] |
Tuesday, February 16, 2010 2:42PM - 2:54PM |
Y10.00007: An Integrating Method for Compton Photon Polarimetry at Jefferson Lab Diana Parno We present a method for measuring the polarization of an electron beam from an asymmetry in the integrated signal of Compton-scattered photons detected in a GSO crystal. We will discuss the design of our data-acquisition system, which integrates the signal by summing FADC samples; compare our simulation results to our test measurements; and show preliminary electron beam polarization data for the $d_2^n$ and HAPPEX-III experiments conducted in 2009. Our method allows improved precision at beam energies as low as 1 GeV, and our data show high stability over months of running and good agreement with other electron beam polarimetry methods. Our work is part of an upgrade to the Compton polarimeter in Hall A of Jefferson Lab; high-precision Compton polarimetry is vital to an extensive experimental program that explores issues ranging from nucleon form factors to the distribution of neutrons in heavy nuclei. [Preview Abstract] |
Tuesday, February 16, 2010 2:54PM - 3:06PM |
Y10.00008: Determination of the linear polarization for pseudo-scalar meson photoproduction experiments in Hall-B at JLab Arthur Sabintsev The JLab CLAS g9a experiments are double polarization measurements that have accumulated photoproduction data using a linearly polarized, tagged photons incident on a longitudinally polarized, frozen spin butanol target (FROST). Linearly polarized photons were produced via coherent bremsstrahlung from an electron beam incident on an oriented diamond crystal.\footnote{U. Timm, Fortschritte der Physik, \textbf{17}, 765 (1969).} The analysis of the resulting coherent peaks was used to determine photon polarization which agree with phenomenological calculations.\footnote{A. Natter, \textit{et al.}, Nuc. Inst Meth B \textbf{211}, 465 (2003).} [Preview Abstract] |
Tuesday, February 16, 2010 3:06PM - 3:18PM |
Y10.00009: The GlueX Detector in HallD at Jefferson Lab Curtis Meyer The GlueX experiment is the major new detector as part of the Jefferson Lab 12-GeV upgrade. The experiment will be housed in a new hall (Hall D), at the end of a new photon-only beamline. Construction started on the detector and Hall in 2009 and is progressing towards completion in 2014. I will present a status report on the construction of Hall D as well as a brief overview of the physics potential of the detector and Hall. [Preview Abstract] |
Tuesday, February 16, 2010 3:18PM - 3:30PM |
Y10.00010: GlueX Data Rates David Lawrence, Mark Ito The GlueX experiment at Jefferson Lab is scheduled to start data taking in 2015. At high luminosity, it will acquire data at 3GB/s and record to disk at 300MB/s, comparable to or greater than LHC experiments. Much of the data will be generated in flash ADCs and compressed online. Current plans on how the system will work and be monitored will be presented. [Preview Abstract] |
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