Abstract
The reaction has been investigated by two independent methods. In the first method the energies of the neutron groups were measured with a proton recoil telescope using an integral range technique. In the second method slow neutrons were observed at the threshold energies for each level with an enriched B counter. The combined results of the two methods give energy levels in at excitation energies of 0.74, 1.31, and 1.72±0.06 Mev, with a ground-state -value for the reaction of -2.82±0.10 Mev. A comparative experiment with a target was carried out so that positive assignment of the levels to could be made. This work confirms the existence of a second excited state in at 1.3-Mev excitation. The 1.3-Mev level had been observed in an early slow-neutron threshold experiment using the reaction, but it has not been found in other reactions leading to the same final nucleus.
- Received 9 November 1955
DOI:https://doi.org/10.1103/PhysRev.101.1373
©1956 American Physical Society