Total reaction and neutron-removal cross sections of (30–60)A MeV Be isotopes on Si and Pb

Total reaction cross sections σ_R of all particle-stable Be isotopes on Si, and several of their neutron-removal cross sections σ_-xn, were measured near (30–60)A MeV by injecting magnetically separated, focused, monoenergetic secondary beams of these projectiles into a telescope containing nine Si transmission detectors. Similar measurements were made for ^10-12Be on Pb, by placing Pb targets between the Si detectors of another telescope. A Glauber analysis of the Be+Si σ_R data, including only nuclear forces, yields rms radii for the Be isotopes in general agreement with those found by other workers. Similar calculations underpredict the σ_R data for Be+Pb, showing the importance of electromagnetic dissociation. A simple microscopic theory reproduces the n-removal cross sections for ¹¹Be and ¹⁴Be on Si, but overpredicts n removal for ¹¹Be on Pb. For ¹²Be incident upon both Si and Pb targets, σ_-2n significantly exceeds σ_-n, as is expected since 1n removal leaves the weakly bound halo nucleus ¹¹Be. A similar effect for ¹⁰Be on Si is attributed to the weak binding of the last neutron of ⁹Be; however, for ¹⁰Be+Pb, σ_-n slightly exceeds σ_-2n.