Boron flux in cosmic rays and its flux ratio to primary species measured with CALET on the International Space Station
Creators: name: Adriani, Oscar
name: Akaike, Yosui
name: Asano, Katsuaki
name: Aaoka, Yoichi
name: Berti, Eugenio
name: Bigongiari, Gabriele
name: Binns, Walter Robert
name: Bongi, Massimo
name: Brogi, Paolo
name: Bruno, Alessandro
name: Cannady, Nicholas
name: Castellini, Guide
name: Checchia, Caterina
name: Cherry, Walter Robert
name: Collazuol, Gianmaria
name: De Nolfo, Georgia A.
name: Ebisawa, Ken
name: Ficklin, Anthony W.
name: Fuke, Hideyuki
name: Gonzi, Sandro
name: Guzik, T. Gregory
name: Hams, Thomas
name: Hibino, Kinya
name: Ichimura, Masakatsu
name: Ioka, Kunihito
name: Ishizaki, Wataru
name: Israel, Martin H.
name: Kasahara, Katsumasa
name: Kataoka, Jun
name: Kataoka, Ryuho
name: Katayose, Yusaku
name: Kato, Chihiro
name: Kawanaka, Norita
name: Kawakubo, Yuta
name: Kobayashi, Kenko
name: Kohri, Kazunori
name: Krawczynski, Henric S.
name: Krizmanic, John F.
name: Maestro, Paolo
name: Marrocchesi, Pier Simone
name: Messineo, Alberto Maria
name: Mitchell, Jason W.
name: Miyake, Shoko
name: Moiseev, Alexander
name: Mori, Masaki
name: Mori, Nicola
name: Motz, Holger Martin
name: Munakata, Kazuoki
name: Nakahira, Satoshi
name: Nishimura, Jun
name: Okuno, Shoji
name: Ormes, Jonathan
name: Ozawa, Shunsuke
name: Pacini, Lorenzo
name: Pacini, Paolo
name: Rauch, Brian Flint
name: Ricciarini, Ricciarini
name: Sakai, Kazuhiro
name: Sakamoto, Takanori
name: Sasaki, Makoto
name: Shimizu, Yuki
name: Shiomi, Atsushi
name: Spillantini, Piero
name: Stolzi, Francesco
name: Sugita, Satoshi
name: Sulaj, Arta
name: Takita, Masato
name: Tamura, Tadahisa
name: Terasawa, Toshio
name: Torii, Shoji
name: Tsunesada, Yoshiki
name: Uchihori, Yukio
name: Vannuccini, Elena
name: Wefel, John P.
name: Yamaoka, Kazutaka
name: Yanagita, Shohei
name: Yoshida, Atsumasa
name: Yoshida, Kenji
name: Zober, Wolfgang V.
Publisher: name: Proceedings of Science
Year: 2023

description: 38th International Cosmic Ray Conference (ICRC2023), 26 July - 3 August, 2023, Nagoya, Japan
description: We present the measurement of the energy spectrum of the boron flux in cosmic rays based on the data collected by the CALorimetric Electron Telescope (CALET) during 7.25 years of operation on the International Space Station. The energy spectrum is measured from 8.4 GeV/n to 3.8 TeV/n with an all calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length and equipped with charge detectors capable of single element resolution. The observed boron flux shows a spectral hardening at the same transition energy E0 ~200 GeV/n of the carbon and oxygen spectra, though B flux has a different energy dependence with respect to C and O. Within the limitations of our data’s present statistical significance, the boron spectral index change is found to be slightly larger than that of carbon and oxygen, which are similar. A corresponding break in the energy dependence of the B/C and B/O flux ratios also supports the idea that the secondary cosmic rays exhibit a stronger hardening than primary ones. Moreover, interpreting our data with a Leaky Box model, we argue that the trend of the energy dependence of the B/C and B/O ratios in the TeV/n region could suggest a possible presence of a residual propagation path length, compatible with the hypothesis that a fraction of secondary B nuclei can be produced near the cosmic-ray source.