Speaker
Description
We report the properties of cosmic ray nuclei from protons to nickel (Z=1--20, 26, and 28) in the rigidity range from 2 GV to 3 TV
collected by the Alpha Magnetic Spectrometer (AMS) on the International Space Station during 15 years of operation. AMS is the
only magnetic spectrometer in space. Unexpectedly, the twenty-one element measured by AMS, from He to Ca and Fe, Ni can be
categorized into four classes, two primary and two secondary, based on their rigidity dependence. AMS found that the primary cosmic
rays He-C-O-Fe-Ni, and Ne-Mg-Si-S belong to two different classes of cosmic rays. AMS also found that the secondary cosmic rays
Li-Be-B and F-P-K belong to another two different classes of cosmic rays. The rigidity dependences of the secondary cosmic rays and
the primary cosmic rays are distinctly different. In particular, above GV the secondary cosmic rays harden twice as much as the primary
cosmic rays. The third group of cosmic rays N, Na, Al, Cl, Ar, and Ca can be described as linear combinations of primary (O, Si) and
secondary (B, F) cosmic rays. Compared with O and Si, the primary cosmic rays C, Ne, Mg, and S were found to have secondary
component, similar to N, Na, and Al. As a result, the C/O, N/O, Ne/Si, Na/Si, Mg/Si, Al/Si, S/Si, Cl/Si, Ar/Si, K/Si, and Ca/Si abundance
ratios at the source are directly determined independent of cosmic ray propagation. AMS found that the lightest and most abundant primary
proton cosmic rays have two components. Measuring the light isotopes, we found that D flux can also be described as a linear combination
of primary (He) and secondary (He) cosmic ray fluxes.
