Performance optimization of cosmic-ray charged particle detector using wavelength shifter fiber

Abstract

Since plastic detectors are easy to fabricate and have good scintillation properties, they have been used as various forms for cosmic-ray detection. Major factors to determine a detector's efficiency are scintillator size, scintillation transfer material, and the photo acceptor equipment. The size of a plastic scintillator and the photo acceptor equipment (photo multiplier tube, photodiode, etc.) can be decided easily in the design process but the scintillation transfer material has to be selected circumspectly. Light guides using Polymethylmethacrylate (PMMA) have a very high transmittance, but are large in size and very expensive, while a wavelength shifter fiber can transfer the scintillation at a decreased transfer efficiency. Therefore, a detector using a wavelength shifter fiber requires a proper optimization for maximum efficiency. In this study, three detectors of 1000x500x10 mm3 size were fabricated. The wavelength shifter fibers were mounted by optical cement into grooves and the detection efficiency for charged particles was evaluated. The main goal was to measure the detection efficiency for cosmic-ray charged particles detector using a wavelength shifter fiber in order to evaluate the possibility of replacing the expensive PMMA light guides. And, this study was compared with efficiency of ATHLET charged particle detector. We are going to prove that we can fabricate a cosmic-ray charged particle detector with a performance identical to an advanced nation's one.