Light-fragment production in p-nucleus interactions at 600 MeV. Astrophysical application

Abstract

The energy spectra of light nuclides ( 1 1 H, 1 2 H, 1 3 H, 2 3 He, 2 4 He) produced in the interaction of 600 MeV protons on various targets (Be, C, Na, Al, Ca, Fe, Au) have been measured at several laboratory angles (30°, 45°, 75°, 105°), by means of ΔE-E telescopes (semiconductor and scintillator detectors). The spectra are fitted with calculated curves derived both from a two-step model and a thermodynamical model of the p-nucleus interaction. Two ranges of nuclear temperature are found: the first one (about (20÷30) MeV) describes the high-energy part of the spectra, the second one (a few MeV) describes the low-energy part (de-excitation of the residual nucleus). These fits are used for the integration over energies and angles, which allows the computation of the total cross-sections and of the fragmentation probabilities. These probabilities are necessary for the study of2H and3He production in the propagation of galactic cosmic rays and their interaction with interstellar matter. We find that the 〈CNO〉 contribution for the production of cosmic He nuclei is not negligible and must be added to the4He contribution. The mean interstellar path length is about 4 g·cm−2. The results obtained with Na and Ca targets should present a biophysical interest.