Properties of Heavy Secondary Fluorine Cosmic Rays: Results from the Alpha Magnetic Spectrometer
M. Aguilar, L. Ali Cavasonza, Matthew S. Allen, B. Alpat, G. Ambrosi, L. Arruda, N. Attig, F. Barão, L. Barrin, A. Bartoloni, Seth Pree, R. Battiston, M. Behlmann, B. Beranek, J. Berdugo, B. Bertucci, V. Bindi, K. Bollweg, B. Borgia, M. Boschini, M. Bourquin, E. F. Bueno, J.D. Burger, W. J. Burger, S. Burmeister, Xudong Cai, M. Capell, J. Casaus, G. Castellini, F. Cervelli, Yuan-Hann Chang, G. M. Chen, G. R. Chen, Hanze Chen, Y. Chen, Lin Cheng, H. Y. Chou, S. Chouridou, V. Choutko, C. H. Chung, C. Clark, G. Coignet, C. Consolandi, A. Contin, C. Corti, Z. Cui, S. Kokou Dadzie, C. Delgado, S. Della Torre, B. Demirköz, L. Derome, S. Di Falco, V. Di Felice, C. Díaz, F. Dimiccoli, P. von Doetinchem, Fei Dong, F. Donnini, M. Duranti, A. I. Egorov, A. Eline, J. H. Feng, E. Fiandrini, P.H. Fisher, V. Formato, C. Freeman, Yu. Galaktionov, C. Gámez, R. J. Garcı́a López, Corrado Gargiulo, H. Gast, M. Gervasi, F. Giovacchini, D. M. Gómez-Coral, J. Gong, C. Goy, Varlen Grabski, D. Grandi, M. Graziani, S. Haino, K. C. Han, R. K. Hashmani, Z. H. He, B. Heber, Timothy H. Hsieh, Jiayu Hu, M. Incagli, W. Jang, Yi Jia, H. Jinchi, K. Kanishev, B. Khiali, G. N. Kim, Th. Kirn, M. Konyushikhin, O. Kounina, A. Kounine, V. Koutsenko, A. Kuhlman, A. Kulemzin
Abstract
Precise knowledge of the charge and rigidity dependence of the secondary cosmic ray fluxes and the secondary-to-primary flux ratios is essential in the understanding of cosmic ray propagation. We report the properties of heavy secondary cosmic ray fluorine F in the rigidity R range 2.15 GV to 2.9 TV based on 0.29 million events collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The fluorine spectrum deviates from a single power law above 200 GV. The heavier secondary-to-primary F/Si flux ratio rigidity dependence is distinctly different from the lighter B/O (or B/C) rigidity dependence. In particular, above 10 GV, the F/Si/B/O ratio can be described by a power law R^{δ} with δ=0.052±0.007. This shows that the propagation properties of heavy cosmic rays, from F to Si, are different from those of light cosmic rays, from He to O, and that the secondary cosmic rays have two classes.