In the double-differential time-of-flight spectrum of emerging neutrons from neutrons incident on ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, a sharp substantital peak was observed whose energy remained constant as the incident neutron energy varied over at least 1.2 MeV. The results show that this peak is almost surely the secondary neutron group in the sequential 2n decay of levels in ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$ where the primary neutron decay (inelastic scattering) is to the ${\mathrm{}(5/2)\mathrm{}}^{\mathrm{-}}$ (7.547 MeV) level in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$ which then decays via a 3-MeV secondary neutron to the ground state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. This reaction appears to be very selective in that from 15.8 MeV to 18.4 MeV the states of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$ do have substantial overlap with ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$ (${\mathrm{}(5/2)\mathrm{}}^{\mathrm{-}}$, 7.547 MeV) coupled to a neutron, whereas from 8 to 18.4 MeV they appear to have small or negligible overlap with the positive parity states of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$ in this region.

• Received 6 November 1986

DOI:https://doi.org/10.1103/PhysRevC.35.855