Title

Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV/n to 2.0 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Authors

O. Adriani, Università degli Studi di Firenze
Y. Akaike, Waseda University
K. Asano, The University of Tokyo
Y. Asaoka, The University of Tokyo
E. Berti, Università degli Studi di Firenze
G. Bigongiari, Università degli Studi di Siena
W. R. Binns, Washington University in St. Louis, McDonnell Center for the Space Sciences
M. Bongi, Università degli Studi di Firenze
P. Brogi, Università degli Studi di Siena
A. Bruno, NASA Goddard Space Flight Center
J. H. Buckley, Washington University in St. Louis, McDonnell Center for the Space Sciences
N. Cannady, University of Maryland, Baltimore County (UMBC)
G. Castellini, Consiglio Nazionale delle Ricerche
C. Checchia, Università degli Studi di Siena
M. L. Cherry, Louisiana State University
G. Collazuol, Università degli Studi di Padova
K. Ebisawa, JAXA Institute of Space and Astronautical Science
H. Fuke, JAXA Institute of Space and Astronautical Science
S. Gonzi, Università degli Studi di Firenze
T. G. Guzik, Louisiana State University
T. Hams, University of Maryland, Baltimore County (UMBC)
K. Hibino, Kanagawa University
M. Ichimura, Hirosaki University
K. Ioka, Yukawa Institute for Theoretical Physics
W. Ishizaki, The University of Tokyo
M. H. Israel, Washington University in St. Louis, McDonnell Center for the Space Sciences
K. Kasahara, Shibaura Institute of Technology
J. Kataoka, Waseda University
R. Kataoka, National Institute of Polar Research
Y. Katayose, Yokohama National University
C. Kato, Shinshu University
N. Kawanaka, Kyoto University
Y. Kawakubo, Louisiana State University

Document Type

Article

Publication Date

6-18-2021

Abstract

The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10 GeV/n to 2.0 TeV/n allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV/n to 2 TeV/n our present data are compatible with a single power law with spectral index -2.60±0.03.

Publication Source (Journal or Book title)

Physical Review Letters

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