The science objectives for CALET

The CALorimetric Electron Telescope, CALET, is a new all-sky electron and gamma ray observatory to be installed on the standard external payload port of the Japanese Experiment Module Exposure Facility (JEM-EF) of the International Space Station (ISS). The high precision measurements of the electron energy spectrum and the particle arrival directions (10 GeV - 20 TeV) enable CALET to detect distinctive features from nearby cosmic-ray electron sources and WIMP dark matter annihilation or decay. The electron observations in the 1 GeV - 10 GeV region also allow solar modulation investigations. The outstanding energy resolution, better than ∼2 % above 100 GeV, is ideal to detect gamma-ray lines and/or spectral signatures from WIMP dark matter through galactic and extra-galactic diffuse gamma-ray observations in the 10 GeV - 10 TeV region. Gamma-ray sources such as SNRs, AGNs, GRBs, and so on are also objectives for CALET to investigate high-energy phenomena. The cosmic-ray spectra of proton, helium, and heavier nuclei up to iron can be measured in the energy range from several 10 GeV to 1000 TeV. In particular, the measurements of the B/C-ratio above 100 GeV will enable CALET to limit cosmic-ray propagation mechanisms. In this paper, we present the scientific prospects of CALET to investigate the origin, acceleration and propagation mechanisms of cosmic rays and conduct a dark matter search.