Proton removal from B-8, C-9, and C-12 on Si at 20-70 MeV/nucleon

Abstract

A Si detector telescope, in which alternating thick and thin Si elements served as both targets and detectors, was used to measure the energy dependence of the inclusive one-proton-removal cross sections sigma(1p) of B-8, C-9, and C-12 on a Si target. A similar detector telescope was used to measure both sigma(1p) and sigma(2p) for C-9; sigma(2p) of C-9 is more than twice as large as sigma(1p) of C-9 and almost as large as sigma(1p) of B-8. The measurements were compared with shell model calculations using eikonal reaction theory. The quenching factors R-s (the ratio of the measurement to the theoretical prediction) for B-8 and C-9 were near unity, as at higher energies. They also agreed with those measured recently for those nuclei on a C target at 75 MeV/nucleon. For C-12 the quenching is greater with R-s=0.44 +/- 0.03. This is comparable to the value 0.53 +/- 0.02 deduced at energies above 1 GeV/nucleon.

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