AMS Observations of Light Cosmic Ray Isotopes and Implications for their Production in the Galaxy

Abstract

Observations of light isotopes in cosmic rays provide information on their origin and propagation in the Galaxy. Using the data collected by AMS-01 in the STS-91 space mission, we compare the measurements on 1 H, 2 H, 3 He and 4 He with calculations for interstellar propagation and solar modulation. These data are described well by a diffusive-reacceleration model with parameters that match the B/C ratio data. Close comparisons are made within the astrophysical constraints provided by the B/C data and within the nuclear uncertainties arising from the production cross sections. Astrophysical uncertainties are expected to be dramatically reduced by future data, but nuclear uncertainties may represent a serious limitation of the model predictions. A diagnostic test for the reliability of the models is given by ratios such as 2 H/ 3 He, 6 Li/ 7 Li or 10 B/ 11 B.