Calorimetric electron telescope (CALET) for the Japanese Exposure Facility on the ISS

Abstract The CALET (CALorimetric Electron Telescope) instrument is proposed for the observation of TeV electrons at the Japanese Experiment Module Exposure Facility (JEM/EF) on the ISS, which is composed of an imaging calorimeter with scintillating fibers and lead plates, and a total absorption calorimeter with BGO logs. Since TeV electrons could reach only from the nearby sources within a distance less than 1 kpc, we can expect that the energy spectrum has a structural component and the arrival directions show an anisotropy. Therefore, we should be able to localize and identify the nearby cosmic-ray sources by the TeV electron observation. We report the status of development of the CALET instrument, which has a capability to observe electrons up to 10 TeV and a proton rejection power of ∼ 10 6 . We expect to observe ∼ 10 3 events over 1 TeV during the 3 years observation. By using the excellent imaging capability of the CALET, gamma-rays over the GeV region and the nuclear components up to 10 15 eV might also be observed.