Simulated performance of CALET on ISS orbit

Calorimetric Electron Telescope, CALET, is being developed to be on board the Japanese Experiment Module Exposed Facility, JEM/EF, of the International Space Station, ISS. Major goals of the mission are to search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and the gamma-rays in 20 MeV - A few TeV. CALET will measure the protons and the nuclei up to 1000 TeV as well. The main detector is composed of Imaging Calorimeter, IMC, Total Absorption Calorimeter, TASC, Silicon Array, SIA, and Anti-Coincidence Detector, ACD, to detect various kinds of particles in very wide energy range. The total absorber thickness is 31 X0 for electromagnetic particles and 1.4 ̧ for protons. To get optimized CALET performance in observing each kind of particles, we have been carrying out Monte Carlo simulation. In this paper, we estimate the trigger rate at the ISS orbit by calculating the cosmic ray flux at an altitude of 400 km. The rate is 37 Hz for the shower trigger over 10 GeV, which is mainly adopted in the CALET mission. An expected performance of detector such as the geometrical factor, the energy resolution, the angular resolution and the electron/proton separation is also presented.