TheCu63(n,2n)Cu62Cross Section as a Function of Neutron Energy near the Threshold

Abstract

Using the $\mathrm{D}\mathrm{}(d,n)\mathrm{}{\mathrm{He}}^3$ reaction produced by 10.5-Mev deuterons to give monoenergetic neutrons, the ${\mathrm{Cu}}^{63}\mathrm{}(n,2n)\mathrm{}{\mathrm{Cu}}^{62}$ reaction has been studied in the vicinity of the threshold. The product of the differential cross section of the former reaction and the activation cross section of the latter is obtained as a function of angle to the bombarding deuteron beam. By calibrating the Geiger counters with beta-particles from ${\mathrm{Cu}}^{66}$ produced by the thermal neutrons on ${\mathrm{Cu}}^{65}$, the data are made absolute in terms of the known thermal capture cross section. Previous measurements of the differential cross section of the $\mathrm{D}\mathrm{}(d,n)\mathrm{}{\mathrm{He}}^3$ reaction allow the ${\mathrm{Cu}}^{63}\mathrm{}(n,2n)\mathrm{}{\mathrm{Cu}}^{62}$ cross section to be given as a function of energy. An extrapolation of the data gives the energy required to remove a neutron from ${\mathrm{Cu}}^{63}$ as 11.2±0.3 Mev.