Energy Calibration of CALET Onboard the International Space Station

Abstract

In August 2015, the CALorimetric Electron Telescope (CALET), designed for long exposure observations of high energy cosmic rays, docked with the International Space Station (ISS) and shortly thereafter began tocollect data. CALET will measure the cosmic ray electron spectrum over the energy range of 1 GeV to 20 TeV with a very high resolution of 2% above 100 GeV, based on a dedicated instrument incorporating an exceptionally thick 30 radiation-length calorimeter with both total absorption and imaging (TASC and IMC) units. Each TASC readout channel must be carefully calibrated over the extremely wide dynamic range of CALET that spans six orders of magnitude in order to obtain a degree of calibration accuracy matching the resolution of energy measurements. These calibrations consist of calculating the conversion factors between ADC units and energy deposits, ensuring linearity over each gain range, and providing a seamless transition between neighboring gain ranges. This paper describes these calibration methods in detail, along with the resulting data and associated accuracies. The results presented in this paper show that a sufficient accuracy was achieved for the calibrations of each channel in order to obtain a suitable resolution over the entire dynamic range of the electron spectrum measurement.

13 pages, 11 figures, published online 4 March 2017

References in corpus (2)

• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• The cosmic-ray electron flux measured by the PAMELA experiment between 1 and 625 GeV

Cited by in corpus (17)

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• Direct Measurement of the Cosmic-Ray Helium Spectrum from 40 GeV to 250 TeV with the Calorimetric Electron Telescope on the International Space Station
• Cosmic-ray Boron Flux Measured from 8.4 GeV$/n$ to 3.8 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station
• Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station
• Development of the photo-diode subsystem for the HERD calorimeter double-readout
• Direct Measurement of the Nickel Spectrum in Cosmic Rays in the Energy Range from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station
• The CALorimetric Electron Telescope (CALET) on the International Space Station: Results from the First Two Years On Orbit
• CALET Search for electromagnetic counterparts of gravitational waves during the LIGO/Virgo O3 run
• Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station
• Measurements of Heavy Cosmic-Ray Nuclei Spectra with CALET on the ISS
• Performance assessment of the HERD calorimeter with a photo-diode read-out system for high-energy electron beams
• Precision spectral measurements of Chromium and Titanium from 10 to 250 GeV$/n$ and sub-Iron to Iron ratio with the Calorimetric Electron Telescope on the ISS
• Tracker-In-Calorimeter (TIC): a calorimetric approach to tracking gamma rays in space experiments