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Volume 301 - 35th International Cosmic Ray Conference (ICRC2017) - High-light Talks
AMS Results on the Properties of the Fluxes of Elementary Particles and Nuclei in Primary Cosmic Rays
A. Kounine
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Pre-published on: 2017 October 23
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Precision measurements by AMS of the fluxes of cosmic ray positrons, electrons, antiprotons,
protons and light nuclei as well as their rations reveal several unexpected and intriguing features. The presented measurements extend the energy range of the previous observations with much increased precision. The new results show that the behavior of fluxes and electrons and positrons at around 300 GeV is consistent with a new source that produce equal amount of high energy electrons and positrons. Surprisingly, in this rigidity range the spectral indices of cosmic ray nuclei, including protons and helium, experience progressive hardening over the rigidity interval of few hundred GV. In addition, in the absolute rigidity range 60-500 GV, the antiproton, proton, and positron fluxes are found to have nearly identical rigidity dependence and the electron flux exhibits different rigidity dependence. The measured ratio of proton-to-Helium fluxes is not constant at high rigidities, whereas the ratios of other primary cosmic ray nuclei such as carbon and oxygen to helium are constant. From the behavior of the flux ratio of beryllium to carbon the age of cosmic rays in the galaxy is found to be ~12 million years, and, remarkably, the measured boron-to-carbon flux ratio is found to follow a single power law, consistent with the Kolmogorov turbulence model of magnetized plasma. Most importantly, AMS continues studies of complex antimatter candidates with stringent detector verification and collection of additional data.
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