The CALorimetric Electron Telescope (CALET) on the International Space Station

Abstract

The CALorimetric Electron Telescope (CALET), developed and operated by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics experiment installed on the International Space Station (ISS). Its mission goals include investigating nearby possible sources of high-energy electrons, elucidating the details of the acceleration and propagation of galactic particles, and detecting potential dark matter signatures. CALET measures cosmic-ray electron+positron flux up to 20 TeV, gamma rays up to 10 TeV, and nuclei with Z=1 to 40 up to 1,000 TeV for the more abundant elements during long-term observations. CALET has performed continuous observations without major interruptions since mid-October 2015, recording approximately 20 million triggered events per month with energies greater than 10 GeV. Here, we present the highlights of CALET observations made over the first three years of operation, namely the electron+positron energy spectrum, the spectra of protons and other nuclei, and gamma-ray observations, including the characterization of on-orbit performance. Some results of the electromagnetic counterpart search for LIGO/Virgo gravitational wave events are also included.