The Calorimetric Electron Telescope (CALET) on the International Space Station: Latest results from the first three-years on orbit
The CALorimetric Electron Telescope (CALET) space experiment, which has been developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating possible nearby sources of high-energy electrons, studying the details of galactic particle propagation and searching for dark matter signatures. The CALET experiment will measure the flux of cosmic-ray electrons (including positrons) up to 20 TeV, gamma-rays up to 10 TeV and nuclei with Z=1 to 40 up to 1,000 TeV. The instrument consists of two layers of segmented plastic scintillators for the cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument was launched on August 19, 2015 to the ISS with an unmanned carrier HTV-5 and installed on the Japanese Experiment Module-Exposed Facility (JEM-EF).
Since the start of operation in mid-October, 2015, a continuous observation has being kept mainly by triggering high energy (>10 GeV) showers without any major interruption. The number of the triggered events over 10 GeV is nearly 20 million per month. By using the data obtained during the first three-years, we will have a summary of the CALET observations: 1) Electron+Positron energy spectrum up to 5 TeV, 2) Proton and Nuclei spectrum up to 100 TeV, 3) Gamma-ray observations, with the performance of observations on orbit. We will present also the results of observations of the electromagnetic counterparts to LIGO-VIRGO gravitational wave events and high-energy counterparts to GRB events measured with the CALET Gamma-ray Burst Monitor (CGBM).