The angular distributions of neutrons to the ground state and to the first excited state of ${\mathrm{B}}^{10}$ in the reaction ${\mathrm{Be}}^9(d, n){\mathrm{B}}^{10}$ have been studied at incident deuteron energies of 1.41 Mev, 1.88 Mev, and 2.35 Mev. A proton recoil spectrometer utilizing a xenon gas scintillation trigger was developed to study this problem. This spectrometer operated with a resolution of the order of 7% at the neutron energies involved in this reaction.

The analysis of the data in terms of a direct interaction mechanism indicates that the results are consistent with an interpretation which indicates that the majority of the neutrons emitted at bombarding energies below the Coulomb barrier originate in the ${\mathrm{Be}}^9$ target nucleus.

• Received 7 July 1960

DOI:https://doi.org/10.1103/PhysRev.120.1369