10B and 11B production cross sections in 12C spallation by protons and alpha particles Application to cosmic ray propagation

The cross sections for boron isotope production in carbon spallation by 40, 50, 150, 600 MeV, 5 GeV protons and 100-160 MeV α particles have been measured. Isotope ratio measurements were performed by sputtering mass spectrometry. An isotope dilution-like method in solid phase was developed for absolute cross section measurements. The present work and previous experimental results allow cosmic ray propagation calculations based mainly on experimental cross section values. The abundances of the light cosmic ray elements were calculated using the ''leaky-box'' model. The calculated values of the boron and lithium isotopic ratios in cosmic rays, practically independent of the propagation assumptions, are found to be independent of the energy from 1 to 100 GeV per nucleon