Optimization of EJ-200 Scintillators' Optical Surface Area for the GlueX Start Counter

ORAL

Abstract

For the GlueX Start Counter to operate at maximum efficiency a time resolution of \textless 350ps is required to identify the electron beam buckets produced by the Continuous Electron Beam Accelerator Facility at Jefferson Lab. Thirty EJ-200 machined scintillator paddles were utilized for the Start Counter due to its fast decay time of 2 ns, long attenuation length, and high light output. The geometry of these paddles consists of a long straight section, a bend section, and a tapered nose section. Over a period of three months, five prototypes were closely monitored for degradation at Florida International University. Fifty scintillators were machined in June of 2014. However, the initial surface quality did not meet our specifications. After several polishing trials, a polishing procedure was established which resulted in an improvement of the overall surface quality and subsequently a vast improvement in time resolution. The optimization of the scintillators optical surface quality and the physical properties of the scintillator paddles will be discussed. This work was supported in part by DoE contracts DE-FG02-99ER41065 and DE-AC05-06OR23177.

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Authors

  • Anthony Llodra

    Florida Intl Univ

  • Brad Cox

    North Carolnia State University, Vanderbilt University, University of South Carolina, University of Virginia, Francis Marion Univ, Oak Ridge National Laboratory, Massachusetts Institute of Technology, Florida International University, Georgia College, JINR, Tsinghua University, LBNL, GANIL, Austin Peay State University, Lehigh University, University of Pardubice, Universit\'e de Rennes, Austin Peay State University Department of Physics and Astronomy, Oak Ridge National Laboratory, Oak Ridge TN 37831, American Superconductor Corp., Westborough MA 01581, University of North Georgia, Dahlonega GA 30597, Florida State University, Ecole Polytechnique, Space Telescope Science Institute, Fermi National Accelerator Lab, National Optical Astronomy Observatory, Austin Peay State Univerity, North Carolna State University, Florida Intl Univ, University of North Georgia, Clemson University, Clemson Univ, Vanderbilt University/ORNL, Vanderbilt University/Univ. of Kentucky, College of William and Mary, Louisiana State University, Presbyterian College, North Carolina State Univ, Department of Physics, Virginia Tech, Mathematical Institute, University of Oxford, Virginia Tech University, Hollins University, University of Tennessee Space Institute, Davidson College, University of Tennessee, American Superconductor Corporation, University of South Alabama, North Carolina State University, James Madison University, Lousiana State University, Korea Electrotechnology Research Institute, Changwon Korea