Abstract
Angular correlations in the reaction have been studied through two-parameter analyses of proton—gamma-ray coincidences at bombarding energies of 4.65, 5.40, and 6.40 MeV. Protons were detected by an annular solid-state detector centered at ; gamma rays were detected with a NaI(Tl) spectrometer for five angles in the range . Branching ratios were determined for nine of the ten levels of MeV; the exception is the 4.74-MeV level, which was not observed. From analysis of angular-correlation data the following spin-parity limitations are obtained for the triplet of levels at MeV: 3.72-MeV level (); 3.79-MeV level (); and 3.84-MeV level (). The preference for an even-parity assignment for the 3.84-MeV level is quite strong. The decay modes of the 3.79-MeV level are consistent with the assumption that this is the member of the group of odd-parity levels which includes those at 1.08 MeV (), 2.10 MeV (), and 3.13 MeV (expected ). For those levels with MeV, the correlation analysis provides restrictions on possible level spins and on multipole-mixing amplitudes for some of the principal deexcitation transitions. These results are consistent with other available information. The 4.65-MeV level of is found to have , and decays by transitions to the 0.94-MeV level () and to the 1.13-MeV level [] with branching ratios of 15 and 85%, respectively. This appears to be the most likely candidate for the , analog of the 3.55-MeV state of . The 4.40-MeV level is also observed to decay to the 1.13-MeV level, and is a possible but less likely candidate for the analog of this level.
- Received 9 December 1966
DOI:https://doi.org/10.1103/PhysRev.156.1145
©1967 American Physical Society