(He4,Be7) Reaction in Magnesium, Aluminum, Titanium, Cobalt, and Copper from Threshold to 42 Mev

Abstract

Cross sections for the production of ${\mathrm{Be}}^7$ in the He-ion bombardment of Mg, Al, Ti, Co, and Cu have been measured in the 30-42-Mev energy range. The excitation functions for these reactions are presented. A study of the bulk (0°-90°; 90°-180°) laboratory angular distributions by the catcher foil technique of the ${\mathrm{Be}}^7$ nuclei emerging from 2.0- and 1.85-mg/${\mathrm{cm}}^2$ magnesium targets and an examination of the approximate range-energy curves for the ${\mathrm{Be}}^7$ particles in aluminum and magnesium indicates that the reaction proceeds through a compound nucleus. The experimental excitation function for the ${\mathrm{Al}}^{27}$(${\mathrm{He}}^4$, ${\mathrm{Be}}^7$)${\mathrm{Na}}^{24}$ reaction is compared with calculations based on the nuclear evaporation model. The cross sections for the production of ${\mathrm{Na}}^{24}$ and ${\mathrm{Be}}^7$ in the He-ion bombardment of aluminum are contrasted and the difference between the yields leads to an excitation function for the (${\mathrm{He}}^4$, ${\mathrm{He}}^3$ ${\mathrm{He}}^4$) reaction.