Carbon Isotopes in the PAMELA Experiment

Abstract

An analysis of the isotopic composition of nuclei in galactic cosmic rays (GCR) in the orbital experiment of the PAMELA collaboration allows us to study the problems of the origin and propagation of cosmic rays in the Galaxy. Due to the high statistical and methodological accuracy, the data of the PAMELA magnetic spectrometer provided significant progress in studying the isotopic composition of 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 of local sources from close ones to the GCR (∼ 100 pc) of recent (∼ 106 yrs) supernova explosions. To date, the isotopic composition of carbon nuclei in the GCR has been measured only for the 13C / 12C ratio in the energy region ∼ 0.05-0.13 GeV / nucleon in the VOYAGER 1.2 space experiment and the upper limit for the 14C / 12C ratio was estimated in the ACE / CRIS experiment for energies 0.12-0.43 MeV / nucleon. In this work, using PAMELA flight data 2006-2014, on the rigidity of the detected nuclei and their speed (time-of-flight analysis and ionization losses in the multilayer calorimeter of the device), an attempt was made to determine the isotopic composition of carbon nuclei in the energy region of ∼ 0.1-1 GeV / nucleon. The half-life of 14C nuclei is 5730 years and can be detected in the case of a supernova explosion in the last ∼ 5 104 years at a distance of ∼ 100 200 pc. The results of isotope analysis of carbon nuclei in GCR (spectra 12C, 13C, 14C and 14C / 12C - ratio depending on the rigidity and energy of the nuclei) in comparison with the existing measurement data will be presented.