Production of $sup 7$Be, $sup 9$Be, and $sup 10$Be in the spallation of $sup 13$C by protons of 150 and 600 MeV

Cross sections were determined for the production of Be isotopes from the spallation of highly enriched /sup 13/C targets by protons of 150 and 6OO MeV. The reasons for undertaking this work are two-fold. First, although /sup 13/C is a relatively minor component of C in the solar system, the interstellar medium, and many stars, there are certain astrophysical environments in which it may be expected to play an important role. Exploding stars are considered as likely candidates as cosmic-ray sources, and it is conceivable that a significant fraction of cosmic-ray C could be /sup 13/C. It is thought that the observed cosmic-ray C is predominantly monoisotopic and probably /sup 12/C, but even if the cosmicray C is pure /sup 12/C spallation of heavier primary nuclides will result in a nonnegligible contribution of secondary /sup 13/C, that can undergo further nuclear reactions in its passage through the interstellar medium. Whilst the extent of /sup 13/C rich matter in the universe is not clear, it was thought interesting to investigate the implications that might follow from spallation processes on such material, and it is thought that the results might provide a test for theoretical models that attempt to describe the nuclearmore » spallation mechanism. Details are given of the experimental technique adopted, and results are summarized in tabular form. Samples of the enriched /sup 13/C were irradiated in the synchrocyclotrons at OrsaY and Cern, with integrated fluxes of ~5 x 10/sup 18/ protons. A sputtering mass spectrometer was used for analysis of Be isotopes, having measured the absolute /sup 7/Be cross section by radiochemical techniques. It was found that the distribution of Be product isotopes differed substantially for /sup 12/C and /sup 13/C targets, and the larger N/Z ratio of /sup 13/C was reflected by a larger average N/Z of the product species: the magnitudes of the shift was surprising. Models are discussed. Implications for the use of the long lived /sup 10/Be isotope as a clock'' in cosmic ray studies are also discussed. It is hoped to extend the studies also to Li and B production. (UK)« less