Abstract
Protons of 16-MeV energy were scattered from isotopically enriched targets of , , and . Differential cross sections were measured for scattering to the ground state and the first and collective states. As the mass number increases, the elastic angular distributions shift towards smaller angles and show increasing damping. The and cross sections show a systematic decrease in magnitude with increasing . Optical-model calculations were made by fixing the geometrical parameters for each set of isotopes and searching on and , the real and surface imaginary parts of the optical potential. The observed trends, systematically increasing with , are consistent with an isospin dependence in the real and imaginary parts of the optical potential. The distorted-wave program dwuck, assuming a collective vibrational model, was run using complex coupling and Coulomb excitation in order to extract deformation parameters for all the and states. These parameters indicate that the decrease in inelastic scattering with increasing is associated with a decreasing collectivity for each set of isotopes. The values of are in reasonable agreement with deformation parameters extracted by other methods.
- Received 18 April 1968
DOI:https://doi.org/10.1103/PhysRev.174.1429
©1968 American Physical Society