Measurement of beryllium isotopic composition in cosmic rays with the AMS-02 experiment on the International Space Station

Cosmic rays are a powerful tool for the investigation of the structure of the magnetic fields in the galactic halo and of the properties of the Inter-Stellar Medium. Two parameters of the cosmic rays propagation models, the galactic halo (half-) thickness, H, and the diffusion coefficient, D, are loosely constrained by current cosmic rays flux measurements, in particular a large degeneracy exists being only H/D well measured. The Be-10/Be-9 isotopic flux ratio (thanks to the 2 My lifetime of Be-10) can be used as a radioactive clock providing the measurement of cosmic rays residence time in the galaxy. This is an important probe to solve the H/D degeneracy. Past measurements of Be-10/Be-9 isotopic flux ratio in CR are scarce, limited to low energy and affected by large uncertainties. In this work, new preliminary measurements of Be-10/Be-9 and complementary Be-7/Be flux ratios are presented, both obtained from the data of the AMS-02 experiment.