Abstract
transitions to the pair of states at 16.64 and 16.90 MeV in have been observed in the reaction . The transitions to both states are resonant at the 17.64- and 18.15-MeV states, which have . The following resonant cross sections and branching ratios have been obtained: μb; ; μb; . From these transitions and the reported strengths for the transitions from the states to the ground and first excited states, the amount of isospin mixing in the four highly excited states has been determined using intermediate-coupling shell-model wave functions. The squared components amount to 40% and 60% in the 16.6- and 16.9-MeV states, and 95% and 5% in the 17.6- and 18.2-MeV states, respectively. Using these mixing coefficients and the assumption of pure character for the ground and first excited states, a shell-model calculation accounts approximately for the strengths of most of the observed or reported magnetic dipole transitions from the 17.64- and 18.15-MeV states. Inclusion of a possible , level at 19.4 MeV improves the agreement. A large nonresonant transition to the 16.6-MeV state with μb can be ascribed to direct radiative proton capture which yields a reduced proton width of for the final state. This transition, and the fact that the equivalent transition to the 16.9-MeV state is not observed, substantiate the predominance of a () configuration for the 16.6-MeV state and agree with an assumed () configuration for the 16.9-MeV level.
- Received 27 December 1967
DOI:https://doi.org/10.1103/PhysRev.173.919
©1968 American Physical Society