Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV$/n$ to 2.2 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station

Abstract

In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10 GeV$/n$ to 2.2 TeV$/n$ with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of $\sim$0.15 around 200 GeV$/n$ established with a significance $>3\sigma$. They have the same energy dependence with a constant C/O flux ratio $0.911\pm 0.006$ above 25 GeV$/n$. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.

main text: 7 pages, 3 figures; supplemental material: 20 pages, 15 figures, 3 tables

References in corpus (11)

• Discrepant hardening observed in cosmic-ray elemental spectra
• Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
• Measurement of the cosmic-ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite
• Spectral breaks as a signature of cosmic ray induced turbulence in the Galaxy
• Origin of the Cosmic Ray Spectral Hardening
• Measurement of boron and carbon fluxes in cosmic rays with the PAMELA experiment
• Energy Spectrum of Cosmic-ray Electron and Positron from 10 GeV to 3 TeV Observed with the Calorimetric Electron Telescope on the International Space Station
• Composition of Primary Cosmic-Ray Nuclei at High Energies
• GeV-TeV cosmic-ray spectral anomaly as due to re-acceleration by weak shocks in the Galaxy
• Energy Calibration of CALET Onboard the International Space Station
• Measurements of Heavy Cosmic-Ray Nuclei Spectra with CALET on the ISS

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