Predicted CALET Measurements of Heavy and Ultra-Heavy Cosmic Ray Nuclei

Abstract

The CALorimetric Electron Telescope (CALET) is a Japanese-Italian-US astroparticle observatory expected to be installed on the ISS in 2015. The main calorimeter (CAL) on CALET is comprised from top to bottom of a charge detector (CHD) with two crossed layers of scintillator paddles, an imaging calorimeter (IMC) with planes of scintillating fibers interleaved with tungsten sheets, and a total absorption calorimeter (TASC) made of lead tungstate logs. The main science objectives of CAL are to measure the combined cosmic ray electron and positron spectrum to 20 TeV, gamma rays to 10 TeV, and nuclei 1 ≤ Z ≤ 40 to 1,000 TeV. In this paper we present the expected numbers of heavy (26 ≤ Z < 30) and ultra-heavy (UH) (30 ≤ Z ≤ 40) Cosmic Ray (CR) nuclei that CAL will measure in a planned 5 year mission in the full detector geometry accounting for geomagnetic screening and interactions in the CHD. We will also present the numbers of UH CR nuclei that it will measure using the expanded acceptance permitted utilizing the earth’s geomagnetic field to screen for events above ∼ 600 MeV/nucleon. Above this threshold the UH charges can be resolved using the CHD with a trajectory correction from the top half of the IMC without the need for energy measurement in the TASC.