The cosmic-ray electron and positron spectrum measured with CALET on the International Space Station
Calet, O. Adriani, Y. Akaike*, K. Asano, Y. Aaoka, E. Berti,
G. Bigongiari, W.R. Binns, M. Bongi, P. Brogi, A. Bruno, N.W. Cannady, G. Castellini, C. Checchia, W.R. 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, K. Ioka, W. Ishizaki, M.H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H.S. Krawczynski, J.F. Krizmanic, P. Maestro, P.S. Marrocchesi, A.M. Messineo, J.W. Mitchell, S. Miyake, A. Moiseev, M. Mori, N. Mori, H.M. Motz, K. Munakata, S. Nakahira, J. Nishimura, S. Okuno, J. Ormes, S. Ozawa, L. Pacini, P. Pacini, B.F. Rauch, R. 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 and W.V. Zoberet al. (click to show)
Pre-published on:
August 18, 2023
Published on:
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Abstract
The CALorimetric Electron Telescope (CALET) has been collecting data on the International Space Station for more than seven years since October 2015. CALET is an all-calorimetric instrument with a total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for the measurement of the electron and positron (all-electron) spectrum well into the TeV energy region. The observed event statistics have increased more than three times since its last publication about the all-electron spectrum to 4.8 TeV in 2018. Based on Monte Carlo simulations, the data analysis effectively rejects background protons, resulting in less than 10% contamination up to the TeV region. The expected systematic errors are investigated. The significance of the cutoff at the TeV region in the energy spectrum, which is expected as a result of radiation loss during propagation, has increased to over 6$\sigma$. By observing the detailed structure in the TeV region of the energy spectrum, we will investigate on the presence of possible nearby cosmic-ray sources. In this paper, we will present the updated all-electron spectrum, and briefly discuss its interpretations.