The propagation of cosmic rays inside our Galaxy plays a fundamental role in shaping their injection spectra into those observed at Earth. One of the best tools to investigate this issue is the ratio of fluxes for secondary and primary species. The Boron-to-Carbon (B/C) ratio, in particular, is a sensitive probe to investigate propagation mechanisms.
Figure 1 and Figure 2 show the Boron and Carbon absolute fluxes and B/C ratio, respectively, measured by PAMELA in the period 2006 July to 2008 March. The results span the range 0.44 – 129 GeV/n in kinetic energy.