CALorimetric Electron Telescope (CALET) proposed for JEM exposed facility on international space station

We are proposing the CALorimetric Electron Telescope (CALET) as a suitable mission on the Exposed Facility (EF) of the Japanese Experiment Module (JEM) which is one of the most characteristic external accommodations on the International Space Station (ISS). Major goal of the mission is the investigation of high energy phenomena in universe by observing the electrons in a few GeV ∼ 10 TeV and the gamma-rays in 20 MeV ∼ 10 TeV. The detector consists of an imaging calorimeter (IMC) and a total absorption calorimeter (TASC). It has a proton-rejection power of ∼ 10⁶ for electrons, and the geometrical factor is nearly 1 m² sr. Since 1998, we have made a conceptual design of the instrument and have been proved CALET to be a promising candidate of future program on JEM-EF. Because CALET is a calorimetric detectors sensor for high-energy cosmic rays with a large surface density, large mass is an essential requirement for its instrumentation. JEM-EF has 10 attach points and 2 among them are capable for heavy payloads up to 2.5 tons. CALET is now being developed as a heavy payload. In this paper, we win outline system design of CALET and discuss its compatibilities as a payload on JEM-EF.