Speaker
Description
Precise knowledge of the spectra of secondary cosmic-ray isotopes provides a powerful tool to constrain cosmic-ray propagation models. In particular, $^3$He isotopes in cosmic rays are produced by interactions of primary $^4$He with the interstellar medium; similarly, lithium and beryllium are mainly produced by the fragmentation of heavier primary cosmic-ray nuclei. Among light isotopes, the radioactive $^{10}$Be, which has half-life comparable to the cosmic-ray residence time in the Galaxy, provides crucial complementary information. We present precision measurements of the fluxes of helium isotopes, $^3$He and $^4$He, lithium isotopes, $^6$Li and $^7$Li, and beryllium isotopes, $^7$Be, $^9$Be and $^{10}$Be, as well as the time dependence of the $^3$He/$^4$He flux ratio, based on data collected by AMS on the International Space Station.