scholarly journals The Alpha Magnetic Spectrometer (AMS) on the international space station: Part II — Results from the first seven years

2020 ◽  
Author(s):  
M. Aguilar ◽  
L. Ali Cavasonza ◽  
G. Ambrosi ◽  
L. Arruda ◽  
N. Attig ◽  
...  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Magnetic Spectrometer ◽  
International Space ◽  
Alpha Magnetic Spectrometer

scholarly journals Observation of Properties of Primary and Secondary Cosmic Rays by the Alpha Magnetic Spectrometer on the International Space Station

2019 ◽  
Vol 208 ◽  
pp. 13002
Author(s):  
Alberto Oliva
Keyword(s):  
Cosmic Rays ◽  
International Space Station ◽  
Spectral Index ◽  
Space Station ◽  
Cosmic Ray ◽  
Magnetic Spectrometer ◽  
Light Nuclei ◽  
International Space ◽  
Rigidity Dependence ◽  
Alpha Magnetic Spectrometer

The Alpha Magnetic Spectrometer (AMS-02) is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and operating continuously since then. With a collection rate of approximately 1.7 × 1010 events/year, and the combined identification capabilities of 5 independent detectors, AMS-02 is able to precisely separate cosmic rays light nuclei (1 ≤ Z ≤ 8). Knowledge of the precise rigidity dependence of the light nuclei fluxes is important in understanding the origin, acceleration, and propagation of cosmic rays. AMS-02 collaboration has recently released the precise measurements of the fluxes of light nuclei as a function of rigidity (momentum/charge) in the range between 2 GV and 3 TV. Based on the observed spectral behaviour, the light nuclei can be separated in three distinct families: primaries (hydrogen, helium, carbon, and oxygen), secondaries (lithium, beryllium, and boron), and mixed (nitrogen). Spectral indices of all light nuclei fluxes progressively harden above 100 GV. Primary cosmic ray fluxes have an identical hardening above 60 GV, of about γ = 0.12 ± 0.04. While helium, carbon and oxygen have identical spectral index magnitude, the hydrogen spectral index shows a different magnitude, i.e. the primary-to-primary H/He ratio is well described by a single power law above 45 GV with index -0.077 ± 0.007. Secondary cosmic ray fluxes have identical rigidity dependence above 30 GV. Secondary cosmic rays all harden more than primary species, and together all secondary-to-primary ratios show a hardening difference of 0.13 ± 0.03. Remarkably, the nitrogen flux is well described over the entire rigidity range by the sum of the primary flux equal to 9% of the oxygen flux and the secondary flux equal to 62% of the boron flux.

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