Boron Isotopes in the PAMELA Experiment

Abstract

Analysis of the isotopic composition of nuclei in galactic cosmic rays (GCR) in the PAMELA orbital international experiment allows us to study the problems of the origin and propagation of cosmic rays in the Galaxy. Due to the high statistical and methodical accuracy, the PAMELA magnetic spectrometer data provided significant progress in the study of the isotopic composition of the light nuclei from H to Be in the GCR in the energy region of ∼0.1–1 GeV/nucleon and, for the first time, made it possible to estimate the contribution in GCR from local (∼100 pc) recent (∼106 years) interstellar sources (LS) from supernova explosions. An isotopic analysis of boron (B) nuclei in the GCR has so far been carried out only in the energy region ∼0.08–0.17 GeV/nucleon in the space experiments Voyager, Ulysses, ACE. In this work using the PAMELA data 2006-2014 about the rigidities of the detected nuclei and their speed (time of flight analysis (TOF) and ionization losses in a multilayer calorimeter) for the first time was made an attempt to determine the 11B/10B ratio in the energy range of ∼0.1–1.0 GeV/nucleon. The new PAMELA data are consistent with existing measurements and those expected from modeling, but the statistical and methodological accuracy of measurements does not allow us to separate the contribution of local boron sources to GCR. The results of the isotope analysis of boron nuclei in the GCR (spectra 10B, 11B and 11B/10B ratio depending on the rigidity and energy of the nuclei) in comparison with the existing measurement data and calculations will be presented.