Status of CALET Ultra Heavy Cosmic Ray Analysis
Abstract
The CALorimetric Electron Telescope (CALET) is a Japanese-Italian-US astroparticle observatory operating on the International Space Station (ISS). CALET was launched on August 19, 2015 and continues to return excellent data. The main calorimeter (CAL) was designed to measure the highest energy cosmic ray electrons from 1 GeV to 20 TeV, but it also measures cosmic-ray (CR) nuclei up to 1,000 TeV and gamma-rays above 10 GeV. The energy spectra of the more abundant CR nuclei through _{26}Fe are measured with the CAL, which also has the dynamic range to measure the abundances of CR nuclei from _{1}H to _{40}Zr. CALET has a ultra-heavy cosmic-ray (UHCR) trigger based on the two scintillator layers of the charge detector (CHD) module and the four top scintillating fiber planes of the imaging calorimeter (IMC) module that provides an expanded geometric acceptance. Rigidity cutoffs from the earth's geomagnetic field can be used to select higher energy events from this trigger that can be resolved without an energy measurement from the bottom total absorption calorimeter (TASC) module, such that in its approved 5 year mission on the ISS CALET will collect a UHCR data set with statistics comparable to that achieved with the first flight of the SuperTIGER balloon-borne instrument in a similar energy range. Preliminary results of the CALET UHCR data analysis show reasonable agreement with SuperTIGER relative abundances of even charge UHCR nuclei, and progress has been made in resolving the odd charge UHCR nuclei as well. The CALET space-based measurements have the benefit that they do not require the corrections for atmospheric interactions that those of SuperTIGER do. They also complement the lower energy space-based UHCR measurements by ACE-CRIS.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2797R