Status of the Top and Bottom Counting Detectors for the ISS-CREAM Experiment

Abstract

It is important to measure the cosmic ray spectra to study the origin, acceleration and propagation mechanisms of high-energy cosmic rays. A payload of the Cosmic Ray Energetics And Mass experiment is scheduled to be launched in 2017 to the International Space Station for measuring cosmic ray elemental spectra at energies beyond the reach of balloon instruments. Top Counting Detector and Bottom Counting Detector (T/BCD) as a two-dimensional detector are to separate electrons from protons for electron/gamma-ray physics. The T/BCD each consists of a plastic scintillator read out by 20 by 20 photodiodes and is placed before and after the Calorimeter, respectively. Energy and hit information of the T/BCD can distinguish shower profiles of electrons and protons, which show narrower and shorter showers from electrons at a given energy. The T/BCD performance has been studied with the Silicon Charge Detector and the calorimeter by using a GEANT3 + FLUKA 3.21 simulation package. By comparing the number of hits and shower width distributions between electrons and protons, we have studied optimal parameters for the e/p separation.