CALET measurements of cosmic ray electrons in the heliosphere

The CALorimetric Electron Telescope (CALET) mission has been proposed to measure electrons and gamma rays in a wide energy range on the Japanese Experiment Module (JEM) /International Space Station (ISS) and approved for the phase A study by the Japan Aerospace Exploration Agency (JAXA). In this paper we present the purposes of the CALET mission pertaining to solar physics and expected results from measurements of electrons in the 1-100GeV energy range. Cosmic rays in this energy region are largely modulated by solar activity and their intensity has both long-term and short-term variations. Measuring such variations precisely will give new information about the transport of cosmic rays in the heliosphere. We estimate the energy dependence of the diffusion of cosmic rays through the solar magnetic field and verify some transport models. Electrons in this energy range are mostly negative though CALET does not distinguish the sign of charges directly. We therefore investigate the charge sign dependence of variations using a correlation between the electron intensity and the neutron monitor counting rate, which indicates the variation of proton intensity. We also expect to detect Forbush decreases in the electron flux. In such decreases, short-term variations of negative charges might differ from those of positive ones.