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 PJ: Instrumentation - Detectors |
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Chair: Eugene Chudakov, Thomas Jefferson National Accelerator Facility Room: Blue Point I |
Saturday, October 26, 2013 10:30AM - 10:42AM |
PJ.00001: Characteristics of SiPM Photo Sensors for GlueX Yi Qiang, Elton Smith, Ivan Tolstukhin, Will Brooks, Hayk Hakobyan, Sergey Kuleshov, Orlando Soto, Alam Toro, George Lolos, Zisis Papandreou, Andrey Semenov The barrel calorimeter of the GlueX detector in Hall D at Jefferson Lab will be instrumented with 3840 large-area (1.2$\times$1.2 cm$^2$) custom silicon photomultiplier (SiPM) arrays manufactured by Hamamatsu Corporation~[1]. These photon sensors have properties similar to vacuum photomultipliers, but are unaffected by high magnetic fields. In our experiment, they will operate in magnetic fields exceeding 1~T. A series of measurements have been carried out by several groups to characterize these SiPMs including the photon detection efficiency (PDE), gain, dark rate, cross talk and after-pulsing at different bias voltages and temperatures. A special study was performed for the first time to separate the cross talk and after pulsing by analyzing ADC spectra with different gate widths. These measurements allow a unique extraction of after-pulsing parameters. We will present a summary of these measurements and the plan for use of these sensors in the GlueX experiment.\\[4pt] [1] F. Barbosa {\em et al.,} NIM A695 (2012) 100. [Preview Abstract] |
Saturday, October 26, 2013 10:42AM - 10:54AM |
PJ.00002: Reconstruction of showers in the GlueX barrel calorimeter William Levine A crucial part of the GlueX meson spectroscopy program is the analysis of reactions involving neutral mesons ($\pi^0$ and $\eta$) decaying into photons. The barrel calorimeter, one of two calorimeters built to detect these photons, is a lead/scintillating fiber calorimeter encircling the target and the tracking detectors, equipped with flash ADC and TDC readout. The reconstruction of the energy and position of electromagnetic showers in the calorimeter will be discussed here. The design and optimization of an algorithm to cluster calorimeter hits together is essential to prevent the reconstruction of spurious showers and the merging of two distinct showers. Also important is the development of a procedure for distinguishing clusters caused by electromagnetic showers from those caused by hadronic showers. [Preview Abstract] |
Saturday, October 26, 2013 10:54AM - 11:06AM |
PJ.00003: The Forward Calorimeter of the GlueX Experiment Daniel Bennett The Forward Calorimeter (FCAL) of the GlueX experiment is a lead glass electromagnetic calorimeter currently being built in Hall D of Jefferson Lab. The GlueX experiment is a photoproduction experiment that will utilize coherent bremsstrahlung radiation to map out the light meson spectrum, including a search for hybrid mesons with exotic quantum numbers ($J^{PC}$). The FCAL will detect photons between $1^{\circ}$ and $10.8^{\circ}$ downstream from the target. The calorimeter is built out of 2800 elements, each of which consists of a lead glass block, an FEU 84-3 PMT, and a custom Cockcroft-Walton electronic base. In the Fall of 2011, a 25 element prototype detector was installed in Hall B of Jefferson Lab to measure the energy and timing resolution of the calorimeter using electrons between 100 and 250 \nolinebreak MeV. The design and construction of FCAL and the results from the prototype test will be discussed. [Preview Abstract] |
Saturday, October 26, 2013 11:06AM - 11:18AM |
PJ.00004: Electromagnetic Calorimeter studies for the GEp(5) experiment Carlos Ayerbe Gayoso The GEp(5) experiment, part of the SBS collaboration, will be the fourth measurement of the $G_{Ep}/G_{Mp}$ ratio using the proton recoil polarization technique. The current data suggests that the $G_{Ep}/ G_{Mp}$ ratio obtained with this technique, might cross zero near $Q^2 \sim$ 10 $GeV^2$, now reachable with the CEBAF upgrade to 12 $GeV$ energy beam. This measurement technique requires a precise measurement of the energy and angles of the scattered electron in coincidence with the recoil proton. The electron's measured energy and crude position will be used in the trigger, while the offline position measurement will be used in kinematic cuts to separate the elastic process from the background. A lead-glass calorimeter, which was used in the previous experiments, is not optimal for the planned experiment due to the rapid radiation damage in the experiment's running conditions. A sampling calorimeter, made of lead and plastic scintillators, is under consideration. Results from a test beam and Monte Carlo simulations of this kind of calorimeter will be presented. [Preview Abstract] |
Saturday, October 26, 2013 11:18AM - 11:30AM |
PJ.00005: A PbWO4-based Neutral Particle Spectrometer in Hall C at 12 GeV JLab Arthur Mkrtchyan, Vardan Tadevosyan, Hamlet Mkrtchyan, Rolf Ent, Tanja Horn Design studies and component tests have been performed to enable a lead tungstate based neutral particle spectrometer (NPS) in Hall C. This NPS is foreseen to act in tandem with the existing high momentum spectrometer (HMS) for precision coincidence experiments with high luminosity. The NPS will be remotely rotatable accessing an angular range between 5.5 and 60 degrees. It would consist of a sweeping magnet and a 25 msr lead tungstate based detector in a temperature controlled frame. Extensive simulations have been performed to verify operation in a high luminosity environment. An active base has been developed to provide an excellent linearity up to rates per lead tungstate crystal above 1 MHz. A radiation test of the readout chain of one crystal has been performed. In this talk we will introduce the NPS, design studies, and discuss the test results and future plans. [Preview Abstract] |
Saturday, October 26, 2013 11:30AM - 11:42AM |
PJ.00006: A high efficiency neutron/proton detector for high-Q$^2$ form factor measurements Brian Quinn, Gregg Franklin, Vahe Mamyan A hadron calorimeter for use with the Super Bigbite Spectrometer in Hall A at Jefferson Lab is in the final stages of design and simulation. It is a {\em shashlik} calorimeter with iron and scintillator layers with wavelength shifter readout. It has been designed to give excellent spatial and timing resolution. Its stable high efficiency for both neutrons and protons will make it a valuable tool for high-Q$^2$ nucleon-coincidence measurements of nucleon form factors. The design will be presented along with results of detailed simulation. [Preview Abstract] |
Saturday, October 26, 2013 11:42AM - 11:54AM |
PJ.00007: Heavy Gas Cerenkov Detector for Jefferson Lab Hall C Wenliang Li The Thomas Jefferson National Accelerator Facility (JLab) has undertaken the 12 GeV Upgrade to double the accelerating energy of its electron beam. This attracts many interesting proposals to probe the quark-gluon nature of nuclear matter at higher energy therefore a new set of equipment are required. A new Super High Momentum Spectrometer (SHMS) is currently under construction for the experimental Hall C. University of Regina is assigned to construct the Heavy Gas Cerenkov Detector as part of SHMS focal plane detectors. This detector will be used as critical component for good pion identification in the SHMS experimental program. In this presentation, we will report the design, current status and expected performance. [Preview Abstract] |
Saturday, October 26, 2013 11:54AM - 12:06PM |
PJ.00008: A Ring Imaging Detector for CLAS 12 at Jefferson Laboratory Fatiha Benmokhtar The energy increase of Jefferson Laboratory's Continuous Electron Beam Accelerator Facility (CEBAF) to 12GeV promises to greatly extend the physics reach of its experiments. This will include an upgrade of the CEBAF Large Acceptance Spectrometer (CLAS) to CLAS12, offering unique possibilities to study internal nucleon dynamics. For this, excellent hadron identification over the full kinematical range is crucial. In the base equipment this is achieved in CLAS12 by Cherenkov and time-of-flight counters. However improved hadron identification at momenta from 3 to 8GeV/c can be obtained by the installation of a Ring Imaging CHerenkov (RICH) detector into the forward region of CLAS12. In this talk I will be introducing the proposed RICH detector and the constraints imposed upon it so it complies with geometry and performance requirements. [Preview Abstract] |
Saturday, October 26, 2013 12:06PM - 12:18PM |
PJ.00009: Central Time -Of-Flight detector for CLAS12 Hall-B upgrade Vitaly Baturin The time-of-flight system for CLAS12 at Hall-B of the Thomas Jefferson National Accelerator Facility will have a refurbished forward-angle detector and a new barrel scintillation detector for the time-of-flight measurements in the central region inside the superconducting 5 T-solenoid. The 92 cm-long barrel with the inner diameter 50 cm is formed by 48 scintillators of a trapezoidal cross-section about 3x3 cm$^2$. Each scintillator is readout by R2083 PMTs from both upstream and downstream sides via a novel focusing light guides 1 m- and 1.6 m-long respectively. Both PMTs of each counter are enclosed into a novel dynamical magnetic shield that allows PMT performance at 1000 G-solenoid fringe fields. The expected timing resolution of this detector is 60 ps that allows pion-kaon and pion-proton separation at 3.3. sigma level up to 0.64 GeV/c and 1.25 GeV/c respectively. [Preview Abstract] |
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