Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session B8: Nuclear Instrumentation and Applications |
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Sponsoring Units: DNP Chair: Gary Westfall, Michigan State University Room: Hyatt Regency Dallas Cumberland A |
Saturday, April 22, 2006 10:45AM - 10:57AM |
B8.00001: Neutron capture cross sections for AFCI at DANCE Rene Reifarth The Detector for Advanced Neutron Capture Experiments (DANCE) is a 160-element 4$\pi $ barium fluoride array designed to study neutron capture on small quantities of radioactive material. It is located on a 20 meter neutron flight path, which views an ``upper tier'' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE). A number of radioactive isotopes under investigation were motivated by the Advanced Fuel Cycle Initiative (AFCI). During the talk the detector will be described, and first results for the neutron capture cross section experiment on $^{240,242}$Pu will be presented. [Preview Abstract] |
Saturday, April 22, 2006 10:57AM - 11:09AM |
B8.00002: Muon Flux at Proposed US Sites for Underground Labs Kregg Philpott Because the next generation of solar neutrino, dark matter, and double beta decay experiments will require sites with extremely low cosmic-ray muon backgrounds, the establishment of a US deep underground laboratory has been under discussion. As some of the proposed sites involve irregular mountain topographies, a detailed calculation of muon production and penetration can be important both in properly positioning a laboratory and in assessing the potential cleanliness of that laboratory. Such calculations can influence engineering decisions, such as the tradeoffs between depth and rock quality and tunneling costs. Following Gaisser's semi-analytic formulation of atmospheric muon production and muon energy loss in rock and employing available Digital Elevation Models, we have evaluated several proposed sites and made comparisons to the existing laboratories at Kamioka and Gran Sasso. Results will be presented for the Henderson (CO), Homestake (SD), and Kimballton (VA) mines, for San Jacinto Peak (CA) and for the Mt. Stuart batholith (Cowboy and Cashmere Mts, WA). [Preview Abstract] |
Saturday, April 22, 2006 11:09AM - 11:21AM |
B8.00003: Reactor Safeguards using Compact Antineutrino Detectors Nathaniel Bowden, Matthew Allen, James Lund, Adam Bernstein, Celsete Winant Fission reactors emit large numbers of antineutrinos and this flux may be useful for the measurement of two quantities of interest for reactor safeguards: the reactor's power and plutonium inventory throughout its cycle. The high antineutrino flux and relatively low background rates means that simple cubic meter scale detectors at tens of meters standoff can record hundreds or thousands of antineutrino events per day. To estimate plutonium content, we exploit the fact that the ingrowth of $\sim $250 kilograms of plutonium in the core during a typical 1.5 year fuel cycle induces a predictable fall-off in the antineutrino rate in that time. Such antineutrino detectors would add online, quasi-real-time bulk material accountancy to the set of reactor monitoring tools available to the IAEA and other safeguards agencies with minimal impact on reactor operations. Our SNL/LLNL collaboration has deployed a prototype safeguards detector at a reactor in Southern California in order to test both the method and the practicality of its implementation in the field. Here I present results from this prototype detector, discuss further steps needed for practical implementation of this technique, and discuss overlap between these measurements and planned experiments to measure theta13. [Preview Abstract] |
Saturday, April 22, 2006 11:21AM - 11:33AM |
B8.00004: Measurement and modeling of dissolved radon as a tracer of ground water flow in a well Vincente Guiseppe, C.T. Hess $^{222}$Rn, a naturally occurring radioactive gas produced in the $^{238}$U decay series, can build-up in rock and dissolve in ground water. Although $^{238}$U and $^{226}$Ra dictate the presence of radon in the rock, the dynamics of ground water systems control dissolved radon in a well. We have measured variation of radon concentrations (up to a factor of 5) while drawing water from a well over 2 hours. We have measured the vertical distributions of radon in nine wells and identified the sources of dissolved radon. We designed and built a discrete interval thief sampler, lowered it desired depths and collected a volume of water to be later analyzed for radon using liquid scintillation. Using borehole geophysical instruments, we determined the location of fractures and the flow in the well as a function of depth. We observed higher radon values at both the locations of fractures as well as where flow is high. The core fragments removed during well-drilling were counted using gamma spectroscopy to determine the concentrations of radionuclides in the $^{238}$U decay series surrounding the well. A mathematical model of the water mixing and flow out of the well predicts the variation of radon measured over time using the measured vertical radon profiles. [Preview Abstract] |
Saturday, April 22, 2006 11:33AM - 11:45AM |
B8.00005: Multigap Resistive Plate Chamber (MRPC) cosmic ray test system for the STAR Time-of-Flight detector Kohei Kajimoto Research and development for a time-of-flight (TOF) subsystem for the STAR detector at RHIC has been underway for the past several years. The TOF system will utilize multigap resistive plate chambers (MRPC) whose excellent time resolution (velocity determination), together with STAR’s Time Projection Chamber (TPC) track information (momentum determination), will considerably extend the particle identification capability of STAR to higher momentum over large angular acceptance. We have constructed a cosmic ray test system comprised of three plastic scintillators, 4 MRPC modules, and TOF prototype electronics in order to investigate the timing resolution that will be characteristic of the entire TOF system. The test setup will be discussed, test data will be described, and the timing analysis technique will be presented. Overall timing resolution of $\sim$90-100~ps for cosmic ray events has been achieved. [Preview Abstract] |
Saturday, April 22, 2006 11:45AM - 11:57AM |
B8.00006: Proposed STAR Time of Flight Readout Electronics and DAQ Joachim Schambach A novel Time-of-Flight (TOF) subsystem is under design for the STAR detector at RHIC. A total of 3840 Multi-gap Resistive Plate Chambers (MRPC) of 6 pads each are distributed over 120 trays. The total number of channels is 23040. Each TOF tray consists of 192 detector channels and three different types of electronic circuit cards, called “TINO”, “TDIG”, and “TCPU”, listed in order of the data flow. Every 30 trays send their data to a “THUB” card that interfaces to the STAR trigger and transmits the data over a fiber to a fiber receiver which is part of STAR DAQ. The TINO contains the analog front end electronics based on a custom IC called NINO. The output of TINO is passed to the TDIG, where the data are digitized (using the CERN HPTDC ASIC). The TCPU formats and buffers the digital detector information. This formatted data is passed to THUB, which transmits it over an optical fiber to a data receiver in the STAR DAQ room. The architecture of this readout chain and DAQ will be described, and first results from prototypes of the component boards will be discussed. [Preview Abstract] |
Saturday, April 22, 2006 11:57AM - 12:09PM |
B8.00007: Front-End Electronics for a Zero Degree Calorimeter Brennan Metzler The Zero Degree Calorimeter for the CMS experiment at the LHC is designed to measure the geometry of Pb-Pb collisions and to detect photons from proton-proton collisions.~ It is a high frequency device that will be run with a 40MHz beam in a high radiation environment with significant electronic noise. An overview of the design of the front-end electronics system for the ZDC will be presented, including descriptions of how PMT signals will be transmitted from the calorimeter to the counting house, how we plan to split the signals and how Charge Integrating and Encoding Analog to Digital Converting (QIE ADC) chips will be utilized to digitize the signals. We will also discuss the high voltage system for the ZDC. [Preview Abstract] |
Saturday, April 22, 2006 12:09PM - 12:21PM |
B8.00008: Development of Multiplexed Analog Shaper Electronics for use with Highly Segmented Silicon Arrays Carl Metelko, Sylvie Hudan, Romualdo deSouza, Andrew Alexander, John Poehlman, Matthew Hodek We report on an electronic system, MASE (Multiplexed Analog Shaper Electronics), designed to simplify the analog processing and readout from a highly segmented silicon detector array. This system focuses on providing good energy resolution and adequate timing information for up to 1024 channels. It consists of 16-channel boards which can be either used independently or as part of a larger system. The analog portion of each channel has low and high gain shapers with associated leading edge discriminators and peak hold circuits. The logic for readout of the analog signals is performed by two FPGA chips located on each board. Readout of MASE channels is multiplexed. Logical signals are transferred via LVDS while the analog signals are sequenced into a multisampling ADC. Signals are also multiplexed for inspection purposes. Shaper gains and discriminator thresholds are adjustable through DACs via a USB interface. Performance characteristics of the prototype module will be described. [Preview Abstract] |
Saturday, April 22, 2006 12:21PM - 12:33PM |
B8.00009: Investigation of Limitations on the Photon Tagging Technique at High Energies. Marianna Gabrielyan The Hall B Jefferson Lab {\em PrimEx} Collaboration is using tagged photons to perform a 1.5\% level measurement of the absolute cross section for the photoproduction of neutral pions in the Coulomb field of a nucleus. In view of the high precision necessary for this experiment, we are investigating the extent of possible limitations on the tagging technique for photon energies of about 5 GeV. These effects arise from two sources--radiative M\o ller scattering in the bremsstrahlung radiator, and incoherent bremsstrahlung, where the recoiling nucleus is left in an excited state or undergoes nucleon knockout. Both of these processes limit the correlation between the energy of the bremsstrahlung photon and the post-bremsstrahlung electron. These studies use the {\em PrimEx} Hall B pair spectrometer, which consists of a pair converter, a dipole magnet, and a segmented array of plastic scintillator telescopes to detect the electron-positron pair. This enables a comparison between the bremsstrahlung photon energy as determined by the pair spectrometer, and that given by the photon tagger. We will present results from the Fall 2004 {\em PrimEx} run and compare to GEANT simulations of the setup. [Preview Abstract] |
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