Relativistic interaction of22Ne and26Mg in hydrogen and the cosmic-ray implications

C. X. Chen, Louisiana State University
S. Albergo, Università degli Studi di Catania
Z. Caccia, Università degli Studi di Catania
S. Costa, Università degli Studi di Catania
H. J. Crawford, Space Sciences Laboratory at UC Berkeley
M. Cronqvist, Space Sciences Laboratory at UC Berkeley
J. Engelage, Space Sciences Laboratory at UC Berkeley
L. Greiner, Space Sciences Laboratory at UC Berkeley
T. G. Guzik, Louisiana State University
A. Insolia, Università degli Studi di Catania
C. N. Knott, University of Minnesota Twin Cities
P. J. Lindstrom, Lawrence Berkeley National Laboratory
M. Mcmahon, Louisiana State University
J. W. Mitchell, NASA Goddard Space Flight Center
R. Potenza, Università degli Studi di Catania
G. V. Russo, Università degli Studi di Catania
A. Soutoul, Département d‘Astrophysique
O. Testard, Département d‘Astrophysique
C. E. Tull, Lawrence Berkeley National Laboratory
C. Tuvé, Università degli Studi di Catania
C. J. Waddington, University of Minnesota Twin Cities
W. R. Webber, New Mexico State University
J. P. Wefel, Louisiana State University

Abstract

The isotopic production cross sections for 22Ne projectiles at 377,581, and 894 MeV nucleon-1 and 26Mg projectiles at 371 and 576 MeV nucleon-1 interacting in a liquid hydrogen target have been measured by the Transport Collaboration at the Lawrence Berkeley Laboratory Heavy-Ion Spectrometer System (LBL HISS) facility. These cross sections are compared with those predicted by semi-empirical formulae. The systematics are studied to develop suitable inputs for calculations of galactic cosmic-ray interstellar transport. These calculations are used to unfold the transport effects from available observations of cosmic-ray CNO isotopes to extract the underlying source composition. With these new cross section measurements, the previously reported enhancement of 18O at the cosmic-ray source, which is sensitive to the cross sections for production from 22Ne and 26Mg and the uncertainties in cross section prediction formulae, may be explained. There is no evidence for an enhancement of 18O when these new cross sections are used in a weighted slab propagation calculation. © 1997. The American Astronomical Society. All rights reserved.