Excitation Function of the ReactionZn64(n, p)Cu64with Neutrons of Energies between 2 and 3.6 Mev

The relative cross section for ${\mathrm{Zn}}^{64}(n, p){\mathrm{Cu}}^{64}$ has been measured by an activation method for neutron energies of 2.0 to 3.6 Mev. The absolute cross section at 3.55-Mev neutron energy is found to be 56.4±9.0 mb by comparing the ${\mathrm{Cu}}^{64}$ positron activity with the amount of ${\mathrm{Si}}^{31}$ formed in the ${\mathrm{P}}^{31}(n, p){\mathrm{Si}}^{31}$ reaction, which has a previously known cross section of 96.2±9.0 mb. The cross section rises monotonically with increasing energy from a value of 12 mb at 2.0 Mev. The experimental results are compared with the predictions of statistical theory; experimental level densities are used in the calculation, but even so the predicted yield is too small. An upper limit of 2 mb is assigned to the cross section for ${\mathrm{Zn}}^{68}(n, \gamma ){\mathrm{Zn}}^{69*}$ at 3 Mev.