12-20 July 2017
Asia/Seoul timezone
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[CRD043] The CALorimetric Electron Telescope (CALET) on the ISS: Preliminary Results from On-orbit Observations since October, 2015


  • Shojii TORI

Primary authors


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 on the International Space Station (ISS). The primary goals of the CALET mission include investigating on the presence of possible nearby sources of high-energy electrons, studying the details of galactic particle propagation and searching for dark-matter signatures. During a two-year mission, extendable to five years, the CALET experiment is measuring the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays 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 cosmic-ray charge identification (CHD), a 3 radiation length tungsten/scintillating-fiber imaging calorimeter (IMC) and a 27 radiation length 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 HTV-5 (H-II Transfer Vehicle 5) and installed on the Japanese Experiment Module - Exposed Facility (JEM-EF) on August 25. Since the start of operation from in mid-October, 2015, continuous observation has been carried out without any major interruption, mainly by triggering on high-energy (>10 GeV) showers. The number of triggered events is about 20 million per month. Using the data obtained so far, we will present a summary of preliminary results from the CALET observations on 1) Electron energy spectrum, 2) Proton and Nuclei spectra, 3) Gamma-ray observations, with results of an on-orbit performance study. We will also present the results of searches with the CALET Gamma-ray Burst Monitor (CGBM) for electromagnetic counterparts to LIGO-VIRGO gravitational wave events and high-energy counterparts to GRB events.