Performance of the CALET prototype: CERN beam test

We are developing the CALET mission to observe high energy cosmic rays at the Japanese Experiment Module/Exposed Facility (JEM/EF) on the International Space Station. The instrument will be flown in 2013, and will be used for 5 years. The primary scientific purpose of CALET is to search for nearby cosmic ray sources and dark matter. We carried out an accelerator beam test with high energy particles with the CALET prototype at the CERN-SPS. The purpose of this test was to assess the detector performance as well as to study the accuracy of the Monte Carlo simulation method. The prototype detector consists of an imaging calorimeter with 256 scintillating fibers and a total absorption calorimeter consisting of 16 PWO logs. The longitudinal structure is similar with the CALET instrument. We used positron and proton beams in the energy region from 6 to 200 GeV, and from 30 to 150 GeV, respectively. Comparing the experimental data with the simulation results, we have measured the energy deposition in each component, the energy resolution, the lateral shower spread and the e/p separation capability.