Angular Distribution of the Ground-State Neutrons from the C13(p, n)N13 and N15(p, n)O15 Reactions

Abstract

The angular distribution of the neutrons from the ${\mathrm{C}}^{13}(p, n){\mathrm{N}}^{13}$ and ${\mathrm{N}}^{15}(p, n){\mathrm{O}}^{15}$ ground-state reactions has been measured in 10° steps from 0° to 150° for incident proton (laboratory) energies of approximately 6.5, 6.9, 7.5, 8.1, 8.6, 8.9, 9.4, 10.6, 11.4, and 12.2 Mev. Additional measurements were made for ${\mathrm{C}}^{13}$ at 5.0, 10.2, 10.9, and 13.3 Mev, and for ${\mathrm{N}}^{15}$ at 5.5, 7.7, 7.8, and 13.6 Mev. A calibrated plastic or stilbene scintillator was used in order to obtain absolute differential cross sections. Time-of-flight techniques on the Liver-more variable energy cyclotron allowed positive identification of the ground-state neutrons. The targets [C${\mathrm{O}}_2$ (58%${\mathrm{C}}^{13}$) and ${\mathrm{N}}_2$ (90% ${\mathrm{N}}^{15}$)] were sufficiently thick to average out the effects of possible compound-nucleus contributions. From preliminary fits to the ${\mathrm{C}}^{13}$ angular distributions, Glendenning and Bloom have inferred an effective neutron-proton interaction inside the nucleus.