Abstract
The cross sections and angular correlations for neutron emission to various states in the residual nucleus, following the reaction, have been measured over the excitation energy range 8–27 MeV at the effective momentum transfer of 0.35 . In the pygmy resonance, neutron emission leads predominantly to the ground and first excited states of while in the giant resonance it leads to population of two higher excited states (12.71 MeV, 15.11 MeV, This is the first direct observation for neutron population of these states. The isospin assignments of the resonances are made as a result of the observed decays. The branching ratio of the transition to the states compared to the total cross section for neutron emission is found to be which is inconsistent with the theoretical predictions of about 50%. Both isospin splitting and the relative and strengths of the giant resonance are obtained for the neutron decay. The angular-correlation parameters for the decay of the giant dipole resonance are very similar for and which provides some support for a weak coupling model in which the giant resonance for proceeds via core excitations in
- Received 24 November 1997
DOI:https://doi.org/10.1103/PhysRevC.60.034309
©1999 American Physical Society