Properties of Cosmic Helium Isotopes Measured by the Alpha Magnetic Spectrometer

Aguilar, M.; Ali Cavasonza, L.; Ambrosi, G.; Arruda, L.; Attig, N.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Bașeǧmez-du Pree, S.; Battiston, R.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bindi, V.; de Boer, W.; Bollweg, K.; Borgia, B.; Boschini, M. J.; Bourquin, M.; Bueno, E. F.; Burger, J.; Burger, W. J.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Castellini, G.; Cervelli, F.; Chang, Y. H.; Chen, G. M.; Chen, H. S.; Chen, Y.; Cheng, L.; Chou, H. Y.; Choutko, V.; Chung, C. H.; Clark, C.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Cui, Z.; Dadzie, K.; Dai, Y. M.; Datta, A.; Delgado, C.; Della Torre, S.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Di Felice, V.; Díaz, C.; Dimiccoli, F.; von Doetinchem, P.; Dong, F.; Donnini, F.; Duranti, M.; Egorov, A.; Eline, A.; Feng, J.; Fiandrini, E.; Fisher, P.; Formato, V.; Galaktionov, Y.; Gámez, C.; García-López, R. J.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Giovacchini, F.; Gómez-Coral, D. M.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guo, K. H.; Haino, S.; Han, K. C.; He, Z. H.; Hsieh, T. H.; Huang, H.; Huang, Z. C.; Incagli, M.; Jang, W. Y.; Jia, Yi; Jinchi, H.; Kanishev, K.; Khiali, B.; Kim, G. N.; Kirn, Th.; Konyushikhin, M.; Kounina, O.; Kounine, A.; Koutsenko, V. et al.
Bibliographical reference

Physical Review Letters

Advertised on:
11
2019
Number of authors
224
IAC number of authors
3
Citations
45
Refereed citations
42
Description
Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of He 3 and He 4 fluxes are presented. The measurements are based on 100 million He 4 nuclei in the rigidity range from 2.1 to 21 GV and 18 million He 3 from 1.9 to 15 GV collected from May 2011 to November 2017. We observed that the He 3 and He 4 fluxes exhibit nearly identical variations with time. The relative magnitude of the variations decreases with increasing rigidity. The rigidity dependence of the He 3 /He 4 flux ratio is measured for the first time. Below 4 GV, the He 3 /He 4 flux ratio was found to have a significant long-term time dependence. Above 4 GV, the He 3 /He 4 flux ratio was found to be time independent, and its rigidity dependence is well described by a single power law ∝R∆ with ∆ =-0.294 ±0.004 . Unexpectedly, this value is in agreement with the B/O and B/C spectral indices at high energies.
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Particle Astrophysics
The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with
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García López