Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session PH: Instrumentation IV |
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Chair: Daniel Bardayan, University of Notre Dame Room: Pearl Ballroom III |
Saturday, October 26, 2013 10:30AM - 10:42AM |
PH.00001: Large acceptance magnetic spectrometer for the 12 GeV$^2$ GEp experiment Evaristo Cisbani GEp5 is the latest of a series of successful JLab experiments that have measured a linear decrease of the electromagnetic proton form factor ratio $G_E/G_M$ with Q$^2$, changing our view of the mechanism of the electron scattering. GEp5 will extend the previous $G_E/G_M$ measurements to higher $Q^2$ where a possible deviations from linearity could be expected; data can be compared with expectations from perturbative QCD and can give new hints on the role of quark orbital angular momentum. To compensate for the large drop of the elastic cross section with $Q^2$, GEp5 needs to run at the highest beam polarization and luminosity, with large acceptance detectors and a high efficiency proton polarimeter. These requirements are fulfilled by the development of a new liquid hydrogen target and the new Super Bigbite Spectrometer (SBS). SBS use a conventional setup with state of the art detectors: an existing dipole magnet (field integral $\le 2$ Tm), properly adapted to reach forward scattering angles; large Gaseous Electron Multiplier (GEM) chambers used as trackers for both the primary proton and the scattered secondary in the polarimeter. A new shashlik calorimeter with high segmentation likely complete the detector setup. Details will be presented at the meeting. [Preview Abstract] |
Saturday, October 26, 2013 10:42AM - 10:54AM |
PH.00002: Time-of-Flight detector for GlueX experiment Alexander Ostrovidov Design and construction of the Time-of-Flight detector (TOF) for the upcoming GlueX experiment at Jefferson Lab will be discussed. TOF is a 2-dimensional wall of 2.5m long scintillator counters with 176 channels of flash ADC and TDC readout. The choice of the wrapping and gluing materials, design of the light guides, selection and performance of the photo multipliers and electronics will be reviewed. Impact of the electromagnetic rates and PMT longevity on the choice of TOF geometry will be discussed. Construction techniques and tools will be presented. Testing methods for individual TOF components as well as completed modules will be shown. The achieved TOF timing resolution in the preliminary cosmic ray tests is 90ps. [Preview Abstract] |
Saturday, October 26, 2013 10:54AM - 11:06AM |
PH.00003: A versatile, continuous-wave laser system for collinear laser spectroscopy at NSCL C. Ryder, P. Mantica, K. Minamisono, D. Rossi, A. Klose, D. Tarazona, R. Strum, M. Hughes A continuous-wave dye-laser system is now available for use at the BEam COoling and LAser Spectroscopy (BECOLA) facility. The new dye laser system will allow for laser probing of atomic nuclei within the visible wavelength range (550-750nm), complementing the present Ti:Sapphire solid-state laser system that is operable in the high-visible to near-infrared wavelengths (700-1000nm). A calibrated He-Ne laser will be used to stabilize the laser wavelength. A laser power controller (LPC) has been placed in the laser light path near the collinear beam line to reduce laser noise and regulate the laser power. Frequency-doubling is accessible for either the Ti:Sapphire- or dye-laser to reach laser wavelengths spanning from UV to NIR. The upgrades to the BECOLA laser system broadens the applicability of nuclear structure measurements via laser-induced fluorescence. [Preview Abstract] |
Saturday, October 26, 2013 11:06AM - 11:18AM |
PH.00004: Gas Ring Cherenkov Detector for 12-GeV Physics at Hall-A Jefferson Lab J. Wilson, A. Ahmidouch, T. Averett, S. Danagoulian, B. Griego, B. Wojtsekhowski, H. Yao, D. Campbell, J. Cooper, C. Foster, A. Jones, D. Locklear, U. Salamonowicz, S. Spratt A Gas Ring Cherenkov (GRINCH) detector is being developed for the JLab Hall-A BigBite spectrometer. The goal is to accommodate high luminosity and high background rates experiments such as the A1n and the GMn experiments. GRINCH is a 1-atm C4F8O-based Cherenkov counter. The Cherenkov ring is reflected by a set of cylindrical mirrors onto a Photon Detector Array (PDA). The PDA consists of 8-9x60 29-mm diameter Electron Tubes 9125B PMTs, which provide timing information. The PMTs are mounted inside a magnetic shielding box to shield against the 15-30 Gauss magnetic field of the spectrometer magnet. Mirrorized plastic reflectors are used to collect the reflected Cherenkov light onto the PMTs. We present the GRINCH design, the results of the simulations leading to the development of the detector, as well as the test results of the prototype for the PDA. [Preview Abstract] |
Saturday, October 26, 2013 11:18AM - 11:30AM |
PH.00005: Performance Results of Quartz Detector for the SuperHMS Spectrometer at Hall\textunderscore C Jefferson Lab Benjamin F. Griego Jr., Abdellah Ahmidouch, Samuel Danagoulian, Demetria Campbell, Sharon Spratt, Charles Perdrisat, Howard Fenker A quartz hodoscope has been constructed for the trigger system of the super High Momentum Spectrometer (SHMS). The latter will play a central in carrying out the 12-GeV physics program at Hall-C Jefferson Lab. The quartz hodoscope consists of twenty one fused silica bars. Each bar is 125 cm long, 5.5-cm wide, 2.5 cm thick, and is viewed by a UV-sensitive PMT on each end. The quartz hodoscope task is to provide a clean detection of charged particles, provide a high level of background suppression, and provide accurate tracking efficiency determination. Test results of the quartz detectors which include light yield, position resolution, and efficiency measurements will be presented. [Preview Abstract] |
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