Lithium and Beryllium Isotopes in the PAMELA Experiment

The isotopic composition of Li and Be nuclei in the 1–5 GV range of rigidities (nuclear energies of 0.1–1.5 GeV/nucleon) is analyzed using PAMELA flight data from 2006–2014 on the rigidity of detected nuclei and their velocities (time-of-flight analysis and ionization losses in the detector’s multilayer calorimeter). The new PAMELA data expand the range of energies in earlier measurements, are consistent with scarce results, and indicate correlated deviations of Li and Be isotope ratios from the GALPROP data for GCRs, which can be interpreted as evidence of contributions from several nearby local sources against the GCR background. Analysis of precision AMS-02 data on the spectra of positrons, antiprotons, and secondary nuclei of Li, Be, and B also indicates correlated increases in intensity at rigidities of ~50–1000 GV, which could also be due to local sources. The contribution from local sources against the GCR background is estimated at levels of tens of percents for rigidities of 1–5 GV and several percent at rigidities of 50–1000 GV.