Angular distributions and 0° excitation curves have been taken of resolved ground-state and first-excited-state neutron groups from the reactions ${\mathrm{Be}}^9(\alpha , n){\mathrm{C}}^{12}$ ($Q=5.71\mathrm{}$ Mev) and ${\mathrm{Be}}^9(\alpha , n){\mathrm{C}}^{12*}$ ($Q=1.28\mathrm{}$ Mev). For the ground-state neutron group, angular distributions were taken at bombarding energies from 2 to 5 Mev, and a 0° excitation curve from 1.7 to 4.8 Mev. For the neutron group to the first excited state of ${\mathrm{C}}^{12}$, angular distributions were taken in the range 4 to 5 Mev, and a 0° excitation curve from 3.1 to 4.8 Mev. Attempts were made to fit the ground-state neutron angular distributions above 4 Mev using compound-nucleus theory.

• Received 7 November 1956

DOI:https://doi.org/10.1103/PhysRev.105.1288