Total reaction cross sections ${\sigma }_R$ of all particle-stable Be isotopes on Si, and several of their neutron-removal cross sections ${\sigma }_{-\mathrm{xn}},$ were measured near $(30\mathrm{}–60)A\hspace{0.5em}\mathrm{MeV}$ by injecting magnetically separated, focused, monoenergetic secondary beams of these projectiles into a telescope containing nine Si transmission detectors. Similar measurements were made for ${}^{10-12}\mathrm{Be}$ on Pb, by placing Pb targets between the Si detectors of another telescope. A Glauber analysis of the $\mathrm{Be}+\mathrm{Si}$ ${\sigma }_R$ 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 ${\sigma }_R$ data for $\mathrm{Be}+\mathrm{Pb},$ showing the importance of electromagnetic dissociation. A simple microscopic theory reproduces the n-removal cross sections for ${}^{11}\mathrm{Be}$ and ${}^{14}\mathrm{Be}$ on Si, but overpredicts n removal for ${}^{11}\mathrm{Be}$ on Pb. For ${}^{12}\mathrm{Be}$ incident upon both Si and Pb targets, ${\sigma }_{-2n}$ significantly exceeds ${\sigma }_{-n},$ as is expected since $1n$ removal leaves the weakly bound halo nucleus ${}^{11}\mathrm{Be}.$ A similar effect for ${}^{10}\mathrm{Be}$ on Si is attributed to the weak binding of the last neutron of ${}^9\mathrm{Be};$ however, for ${}^{10}\mathrm{Be}+\mathrm{Pb},$ ${\sigma }_{-n}$ slightly exceeds ${\sigma }_{-2n}.$

• Received 8 March 2001

DOI:https://doi.org/10.1103/PhysRevC.64.044611