CALET measurements with cosmic nuclei: expected performances of tracking and charge identification

Abstract

CALET is a space mission currently in the final phase of preparation for a launch to the International Space Station (ISS), where it will be installed on the Exposed Facility of the Japanese Experiment Module (JEM-EF). In addition to high precision measurements of the electron spectrum, CALET will also perform long exposure observations of cosmic nuclei from proton to iron and will detect trans-iron elements with a dynamic range up to Z = 40. The energy measurement relies on two calorimeter systems: a fine grained imaging calorimeter (IMC) followed by a total absorption calorimeter (TASC) for a total thickness of 30 X₀ and 1.3 proton interaction length. A dedicated module (a charge detector, CHD), placed at the top of the apparatus, identifies the atomic number Z of the incoming cosmic ray. In this paper, the IMC performances in providing tracking capabilities and a redundant charge measurement by multiple ᵈᴱ/dx samples are studied for the case of proton and He identification with a preliminary version of the analysis. The CALET mission is funded by the Japanese Space Agency (JAXA), the Italian Space Agency (ASI), and NASA.