Extended measurement of the proton spectrum with CALET on the International Space Station

Kobayashi, K.; Marrocchesi, P. S.; Adriani, O.; Akaike, Y.; Asano, K.; Asaoka, Y.; Berti, E.; Betti, P.; Bigongiari, G.; Binns, W. R.; Bongi, M.; Brogi, P.; Bruno, A.; Cannady, N.; Castellini, G.; Checchia, C.; Cherry, M. L.; Collazuol, G.; De Nolfo, G. A.; Ebisawa, K.; Ficklin, A. W.; Fuke, H.; Gonzi, S.; Guzik, T. G.; Hams, T.; Hibino, K.; Ichimura, M.; Israel, M. H.; Kasahara, K.; Kataoka, J.; Kataoka, R.; Katayose, Y.; Kato, C.; Kawanaka, N.; Kawakubo, Y.; Kohri, K.; Krawczynski, H. S.; Krizmanic, J. F.; Maestro, P.; Mattiazzi, M.; Messineo, A. M.; Mitchell, J. W.; Miyake, S.; Moiseev, A. A.; Mori, M.; Mori, N.; Motz, H. M.; Munakata, K.; Nakahira, S.; Nishimura, J.; Negro, M.; Okuno, S.; Ormes, J. F.; Ozawa, S.; Pacini, L.; Papini, P.; Rauch, B. F.; Ricciarini, S. B.; Sakai, K.; Sakamoto, T.; Sasaki, M.; Shimizu, Y.; Shiomi, A.; Spillantini, P.; Stolzi, F.; Sugita, S.; Sulaj, A.; Takita, M.; Tamura, T.; Terasawa, T.; Torii, S.; Tsunesada, Y.; Uchihori, Y.; Vannuccini, E.; Wefel, J. P.; Yamaoka, K.; Yanagita, S.; Yoshida, A.; Yoshida, K.; Zober, W. V.

doi:10.22323/1.501.0059

The Calorimetric Electron Telescope (CALET) is conducting direct measurements of the main components of high-energy cosmic rays up to ~1 PeV to achieve a systematic understanding of cosmic-ray acceleration and propagation. The detector, consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter, is located on the International Space Station. The thickness of the calorimeter is equivalent to 30 radiation lengths and to ~1.3 proton interaction lengths. Data taking started in October 2015 and has continued stably without any major issues. We present the latest result of our proton spectrum analysis in the energy region from 50 GeV to 100 TeV. The energy resolution for protons is 30-40%. Compared to our previous result published in Physical Review Letters in 2022, the statistics have been increased by more than a factor of 1.5 and the energy range has been extended.

Extended measurement of the proton spectrum with CALET on the International Space Station / K. Kobayashi, P.S. Marrocchesi, O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, P. Betti, G. Bigongiari, W.R. Binns, M. Bongi, P. Brogi, A. Bruno, N. Cannady, G. Castellini, C. Checchia, M.L. Cherry, G. Collazuol, G.A. de Nolfo, K. Ebisawa, A.W. Ficklin, H. Fuke, S. Gonzi, T.G. Guzik, T. Hams, K. Hibino, M. Ichimura, M.H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kohri, H.S. Krawczynski, J.F. Krizmanic, P. Maestro, M. Mattiazzi, A.M. Messineo, J.W. Mitchell, S. Miyake, A.A. Moiseev, M. Mori, N. Mori, H.M. Motz, K. Munakata, S. Nakahira, J. Nishimura, M. Negro, S. Okuno, J.F. Ormes, S. Ozawa, L. Pacini, P. Papini, B.F. Rauch, S.B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J.P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, W.V. Zober. - In: POS PROCEEDINGS OF SCIENCE. - ISSN 1824-8039. - ELETTRONICO. - 501 - 39th International Cosmic Ray Conference (ICRC2025):(2025), pp. 0-0. ( 39th International Cosmic Ray Conference, ICRC 2025 Geneva, Switzerland 15-24 July 2025) [10.22323/1.501.0059].