@article{82fdb3317fe24e249a0bde730c59d5fd,
title = "Observation of spectral structures in the flux of cosmic ray protons with CALET on the International Space Station",
abstract = "A precise measurement of the cosmic-ray proton spectrum is carried out with the Calorimetric Electron Telescope (CALET) and a sharp softening of the energy spectrum above 10 TeV is observed. CALET, located on the International Space Station, has started data taking in October 2015 and has accumulated data for more than seven years without any serious troubles. CALET is pursuing the direct measurement of the main components of high energy cosmic rays up to ~1 PeV in order to understand the cosmic ray acceleration and propagation. Thanks to the thick calorimeter that corresponds to 30 radiation lengths and to ∼1.3 proton interaction lengths, the proton analysis presented in this paper spans a broad energy range from 50 GeV to 60 TeV. Proton energy resolution is 30-40%, and the residual background is less than 10% in the E < 10 TeV region. In the multi-TeV region, we observed a spectral softening with a spectral index change from -2.6 to -2.9 in addition to the spectral hardening we had previously confirmed with a high significance above a few hundred GeV. The transition to the softer regime is much sharper than the smooth onset of hardening observed at lower energy.",
author = "{CALET collaboration} and Kazuyoshi Kobayashi and Marrocchesi, {Pier Simone} and O. Adriani and Y. Akaike and K. Asano and Y. Asaoka and E. Berti and G. Bigongiari and Binns, {W. R.} and M. Bongi and P. Brogi and A. Bruno and N. Cannady and G. Castellini and C. Checchia and Cherry, {M. L.} and G. Collazuol and {de Nolfo}, {G. A.} and K. Ebisawa and Ficklin, {A. W.} and H. Fuke and S. Gonzi and Guzik, {T. G.} and T. Hams and K. Hibino and M. Ichimura and K. Ioka and W. Ishizaki and Israel, {M. H.} and K. Kasahara and J. Kataoka and R. Kataoka and Y. Katayose and C. Kato and N. Kawanaka and Y. Kawakubo and K. Kobayashi and K. Kohri and Krawczynski, {H. S.} and Krizmanic, {J. F.} and P. Maestro and Marrocchesi, {P. S.} and Messineo, {A. M.} and Mitchell, {J. W.} and S. Miyake and Moiseev, {A. A.} and M. Mori and N. Mori and Motz, {H. M.} and K. Munakata and S. Nakahira and J. Nishimura and S. Okuno and Ormes, {J. F.} and S. Ozawa and L. Pacini and P. Papini and Rauch, {B. F.} and Ricciarini, {S. B.} and K. Sakai and T. Sakamoto and M. Sasaki and Y. Shimizu and A. Shiomi and P. Spillantini and F. Stolzi and S. Sugita and A. Sulaj and M. Takita and T. Tamura and T. Terasawa and S. Torii and Y. Tsunesada and Y. Uchihori and E. Vannuccini and Wefel, {J. P.} and K. Yamaoka and S. Yanagita and A. Yoshida and K. Yoshida and Zober, {W. V.}",
note = "Publisher Copyright: {\textcopyright} Copyright owned by the author(s) under the terms of the Creative Commons.; 38th International Cosmic Ray Conference, ICRC 2023 ; Conference date: 26-07-2023 Through 03-08-2023",
year = "2024",
month = sep,
day = "27",
language = "English",
volume = "444",
journal = "Proceedings of Science",
issn = "1824-8039",
}