Solar Modulation During the Descending Phase of Solar Cycle 24 Observed with CALET on the International Space Station

Miyake, S.; Adriani, O.; Akaike, Y.; Asano, K.; Asaoka, Y.; Berti, E.; Bigongiari, G.; Binns, W. R.; Bongi, M.; Brogi, P.; Bruno, A.; Buckley, J. H.; Cannady, N.; Castellini, G.; Checchia, C.; Cherry, M. L.; Collazuol, G.; Ebisawa, K.; Ficklin, A. W.; Fuke, H.; Gonzi, S.; Guzik, T. G.; Hams, T.; Hibino, K.; Ichimura, M.; Ioka, K.; Ishizaki, W.; Israel, M. H.; Kasahara, K.; Kataoka, J.; Kataoka, R.; Katayose, Y.; Kato, C.; Kawanaka, N.; Kawakubo, Y.; Kobayashi, K.; Kohri, K.; Krawczynski, H. S.; Krizmanic, J. F.; Maestro, P.; Marrocchesi, P. S.; Messineo, A. M.; Mitchell, J. W.; Miyake, S.; Moiseev, A. A.; Mori, M.; Mori, N.; Motz, H. M.; Munakata, K.; Nakahira, S.; Nishimura, J.; de Nolfo, G. A.; Okuno, S.; Ormes, J. F.; Ospina, N.; 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.

The CALorimetric Electron Telescope (CALET) installed on the International Space Station has multiple event trigger modes for measuring cosmic-ray (CR) particles and gamma rays, and the observations of the low-energy CRs have been successfully performed by a Low-Energy Electron (LEE) shower trigger mode that is active only at high geomagnetic latitude. Here we have analyzed the low-energy electrons and protons to investigate the solar modulation during the descending phase of the solar cycle 24. We have confirmed that the flux of the low-energy electrons measured by CALET during the solar minimum has reached its maximum, which is comparable to or exceeding the maximum flux observed with PAMELA in the previous solar minimum period. We have also found count rates of electrons and protons at the same average rigidity showing a clear charge sign dependence as expected from the drift model of the solar modulation.

Solar Modulation During the Descending Phase of Solar Cycle 24 Observed with CALET on the International Space Station / Miyake S.; Adriani O.; Akaike Y.; Asano K.; Asaoka Y.; Berti E.; Bigongiari G.; Binns W.R.; Bongi M.; Brogi P.; Bruno A.; Buckley J.H.; Cannady N.; Castellini G.; Checchia C.; Cherry M.L.; Collazuol G.; Ebisawa K.; Ficklin A.W.; Fuke H.; Gonzi S.; Guzik T.G.; Hams T.; Hibino K.; Ichimura M.; Ioka K.; Ishizaki W.; Israel M.H.; Kasahara K.; Kataoka J.; Kataoka R.; Katayose Y.; Kato C.; Kawanaka N.; Kawakubo Y.; Kobayashi K.; Kohri K.; Krawczynski H.S.; Krizmanic J.F.; Maestro P.; Marrocchesi P.S.; Messineo A.M.; Mitchell J.W.; Miyake S.; Moiseev A.A.; Mori M.; Mori N.; Motz H.M.; Munakata K.; Nakahira S.; Nishimura J.; de Nolfo G.A.; Okuno S.; Ormes J.F.; Ospina N.; 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.. - In: POS PROCEEDINGS OF SCIENCE. - ISSN 1824-8039. - ELETTRONICO. - 395:(2022), pp. 1270.1-1270.8.