The neutron-transfer reaction, ${\mathrm{N}}^{14}$(${\mathrm{N}}^{14}$,${\mathrm{N}}^{13}$)${\mathrm{N}}^{15}$, was investigated from 6° to 60° c.m. with 28-Mev ${\mathrm{N}}^{14}$ ions accelerated in the Oak Ridge 63-inch cyclotron. Circular strips of aluminum foil, each encompassing a known angular increment, were used to stop the radioactive ${\mathrm{N}}^{13}$ (10-min). Excited states in ${\mathrm{N}}^{13}$ are unstable with respect to proton emission; the first excited state in ${\mathrm{N}}^{15}$ is 5.28 Mev above ground. Therefore, ${\mathrm{N}}^{13}$ nuclei resulting from transfers to the ground state of ${\mathrm{N}}^{15}$ are at least 5 Mev more energetic than those resulting from transfers to ${\mathrm{N}}^{15}$ excited states. The two groups of ${\mathrm{N}}^{13}$ particles were distinguished by placing suitable absorbers in front of the aluminum catcher foils. It was found that transfers to excited states become more abundant relative to ground state transfers as the incident ${\mathrm{N}}^{14}$ energy is lowered.

• Received 9 September 1960

DOI:https://doi.org/10.1103/PhysRev.121.1190