Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session C15: Instrumentation I |
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Sponsoring Units: DNP Chair: Bogdan Wojtsekhowski, Jefferson Laboratory Room: Key 11 |
Saturday, April 11, 2015 1:30PM - 1:42PM |
C15.00001: 9125B ET Photomultiplier Tubes with a Wavelength Shifting Paint for a Gas Cherenkov Counter Scott Barcus, Todd Averett, Bogdan Wojtsekhowski This presentation will describe a method to increase the amount of Cherenkov light detected by photomultiplier tubes using a wavelength shifting paint and Electron Tubes' 9125B PMTs. A Cherenkov spectrum was generated via cosmic rays striking a polished rectangular fused silica crystal and observed by PMTs. By applying a wavelength shifting paint to the faces of the PMTs photons outside of the normal sensitivity range for the PMTs can be shifted into the sensitive range. A number of PMTs were tested with and without the paint to observe the change in the detected number of Cherenkov photons. The wavelength shifting paint was found to increase the number of photoelectrons seen by as much as 50$ \% $. However, the response of individual tubes was found to be highly variable ranging from increases in light of 5 - 50$ \% $ with an average of 22.4$ \% $. The variable nature of the PMTs' responses indicates that tubes may still need to be individually tested after the paint is applied to select the most desirable tubes. This method can be applied to the PMTs in a gas Cherenkov detector to increase the number of photons collected. [Preview Abstract] |
Saturday, April 11, 2015 1:42PM - 1:54PM |
C15.00002: Construction of a hadron calorimeter for Jefferson Lab Hall-A Super Bigbite Spectrometer Vahe Mamyan A ``shashlik'' hadron calorimeter is being constructed for the new Super Bigbite Spectrometer in Jefferson Lab Hall-A. The calorimeter will be used in nucleon-coincidence form-factor experiments taking advantage of Jefferson Labs' 12 GeV upgrade. An adiabatic light guide has been developed for the calorimeter based on laser cut acrylic sheets. A prototype module has been built to measure time resolution of the calorimeter for cosmic ray muons as well as to validate the Geant4 simulation. Several innovations in the calorimeter design will be discussed, in particular the choice of the scintillator, wave length shifter and the construction process of the light. The results of prototype tests is compared with Geant4 simulation for cosmic ray muons and prediction of HCal time and special resolution for hadrons in the 2-10 GeV/c momentum range will be presented. [Preview Abstract] |
Saturday, April 11, 2015 1:54PM - 2:06PM |
C15.00003: Precision Optics Optimization for GMp Experiment Yang Wang, Kalyan Allada, Todd Averett, Eric Christy, Chao Gu, Min Huang, Bogdan Wojtsekhowski The GMp experiment aims to improve the precision on the elastic e-p cross section measurement to 2{\%}; up to a factor of 5 better than previous measurements, with four-momentum transfer up to 14 $GeV^{2}$ using the High Resolution Spectrometers (HRS) of Hall A at Jefferson Lab. These measurements will be an important benchmark for many other cross section measurements in hadron physics. To reach this goal, it is necessary to improve the precision of many instrument systems. Knowledge of the magnetic optics of HRS is critically important for precision reconstruction of the momentum and coordinates of the scattered particles at the interaction vertex. In this talk, an improved optimization method for optics will be presented in detail and the results of a study based on recent commissioning data in 2014 will be discussed. [Preview Abstract] |
Saturday, April 11, 2015 2:06PM - 2:18PM |
C15.00004: GEANT4 simulation of APEX background radiation and shielding Maduka M. Kaluarachchi, Gordon D. Cates, B. Wojtsekhowski The A$^\prime$ Experiment (APEX), which is approved to run at the Thomas Jefferson National Accelerator Facility (JLab) Hall A, will search for a new vector boson that is hypothesized to be a possible force carrier that couples to dark matter. APEX results should be sensitive to the mass range of 65 MeV to 550 MeV, and high sensitivity will be achieved by means of a high intensity 100 $\mu$A beam on a 0.5 g/cm$^2$ Tungsten target resulting in very high luminosity. The experiment should be able to observe the A$^\prime$ with a coupling constant $\alpha^\prime$ $\sim$ 1$\times$10$^7$ times smaller than the electromagnetic coupling constant $\alpha$. To deal safely with such enormous intensity and luminosity, a full radiation analysis must be used to help with the design of proper radiation shielding. The purpose of this talk is to present preliminary results obtained by simulating radiation background from the APEX experiment using the 3D Monte-Carlo transport code Geant4. Included in the simulation is a detailed Hall A setup: the hall, spectrometers and shield house, beam dump, beam line, septa magnet with its field, as well as the production target. The results were compared to the APEX test run data and used in development of the radiation shielding for sensitive electronics. [Preview Abstract] |
Saturday, April 11, 2015 2:18PM - 2:30PM |
C15.00005: Using BigBite to Detect DIS Electrons for the MARATHON Experiment Tyler Hague The MARATHON experiment will use the BigBite Spectrometer to extract $F_{2}^{n}/F_{2}^{p}$ from the inelastic cross section ratio of 12 GeV electrons on the mirror nuclei $^{3}$He and $^{3}$H. The BigBite Spectrometer consists of a series of detectors to detect electrons and an array of electronics (the ``Front End'') to create triggers in the Data Acquisition System (DAQ). BigBite uses two multi-wire drift chambers to determine the track of particles passing through it, a scintillator array for timing, and two lead-glass detectors for particle identification and a measurement of energy deposition. The Front End uses a series of logic units to create triggers for the DAQ when certain combinations of detectors fire. In this talk an overview of the detectors of the BigBite spectrometer and its Front End electronics setup will be presented. This work is supported by Kent State University, NSF Grant PHY-1405814, and DOE Contract DE-AC05-06OR23177. [Preview Abstract] |
Saturday, April 11, 2015 2:30PM - 2:42PM |
C15.00006: Upgrade of the Cherenkov Detector of the JLab Hall A BigBite Spectrometer Michael Nycz The BigBite Spectrometer of the Hall A Facility of Jefferson Lab will be used in the upcoming MARATHON experiment at Jefferson Lab to measure the ratio of neutron to proton F$_{2}$ inelastic structure functions and the ratio of up to down, d/u, quark nucleon distributions at medium and large values of Bjorken x. In preparation for this experiment, the BigBite Cherenkov detector is being modified to increase its overall efficiency for detecting electrons. This large volume counter is based on a dual system of segmented mirrors reflecting Cherenkov radiation to twenty photomultipliers. In this talk, a description of the detector and its past performance will be presented, along with the motivations for improvements and their implementation. An update on the status of the rest of the BigBite detector package, will be also presented. Additionally, current issues related to obtaining C$_{4}$F$_{8}$O, the commonly used radiator gas, which has been phased out of production by U.S. gas producers, will be discussed. This work is supported by Kent State University, NSF Grant PHY-1405814, and DOE Contract DE-AC05-06OR23177. [Preview Abstract] |
Saturday, April 11, 2015 2:42PM - 2:54PM |
C15.00007: Particle Transportation Through the JLab Hall A BigBite Spectrometer Sheren Alsalmi The BigBite spectrometer of the Hall A Facility of Jefferson Lab is under refurbishment for use in an experiment (E120-10-103) to measure deep inelastic electron scattering off helium-3 and tritium mirror nuclei in the valence quark region (high Bjorken x range). The experiment will use an 11 GeV upgraded beam to determine the ratio of the neutron to proton F2 inelastic structure functions, and the ratio of the down to up quark, d/u, quark probability distributions in the nucleon. The BigBite spectrometer is based on a custom-shaped dipole magnet, which provides for large momentum and angular acceptances needed for the above measurements. Simulations using a ROOT-based Monte Carlo model for tracking and visualizing scattered electrons passing through the BigBite magnet will be presented. The optics parameters of the dipole magnet have been extracted from a field map produced by a TOSCA magnetostatics calculation. The simulations are necessary to estimate the phase space of the scattered electrons inside the relocated detectors of the spectrometer, and check for electrons which could possibly miss a detector and escape detection. This work is supported by Saudi Arabian Cultural Mission SACM , Kent State University, NSF Grant PHY-1405814, and DOE Contract DE-AC05-06OR23177. [Preview Abstract] |
Saturday, April 11, 2015 2:54PM - 3:06PM |
C15.00008: Simulation Study of RICH Detector for Particle Identification in Forward Region at Electron-Ion Collider Cheuk-Ping Wong eRD11 R\&D program is focusing on the technology exploration for hadron particle identification in the forward region of Electron-Ion Collider (EIC) for studying quark and gluon distributions inside the nucleon. A modular Ring Imaging Cherenkov (RICH) detector has been extensively studied in Geant4-based simulation. The detector consists of a block of aerogel, Fresnel lens, four side mirrors and a photosensor plane. The simulated performance of this detector will be presented in this talk. [Preview Abstract] |
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