Search

The reaction 12 C( 3 He, α) 11 C was studied at the bombarding energies of 24.0, 29.2, 34.7 and 39.6 MeV and differential cross sections were analyzed in DWBA and CCBA. The large strength of shell-model-forbidden transition to the 5/2 - state was found to be well explained by the multi-step processes including inelastic channels.

The 28 Si ( 3 He, d) 29 P reaction has been studied at an incident energy of 29.3 MeV. Comparisons of DWBA and CCBA analyses of angular distributions for low-lying bound states show that channel-coupling effect is not important except for stripping to the 1.95-MeV 5/2 + state. Angular distributions for resonance states are analyzed by using Gamow functions as form factors for DWBA calulations. Such a description gives a reasonable account of the experimental angular distributions except that it fails to reproduce experimentally observed j -dependence.

Angular distributions of elastic and inelastic scatterings on 28,29,30 Si were measured with a 51.9 MeV proton beam. The blocking effect in the core-excitation of 29 Si due to the antisymmetrization between the excited-core and the extra neutron was investigated. Optical model and distorted wave Born approximation analyses were performed using a macroscopic form factor for a collective excitation of 28,29,30 Si and a microscopic form factor for a single particle excitation of 29 Si. In the case of 29 Si, a mixing of an excited-core state and a single particle state was taken into account following the intermediate-coupling model calculation. Deformation parameters β 2 of 28,29,30 Si were extracted to be 0.42, 0.36 and 0.36, respectively. The reduction in the deformation parameter of 29 Si is considered to manifest the blocking effect of 25±14% in the core-excitation.

The measurements were made at angles of the center of mass extending from 14° to 128° or 172°. The yield of inelastic scattering at most angles was of the same order in the elastic scattering. A Thomas type spin-orbit coupling of the optical potential is useful for the elastic scattering at backward angles. Discrete and continuous ambiguities in the optical model parameters appeared in the analysis. The experimental values of inelastic scattering were predicted fairly well by the DWBA theory, and the deformation parameters β 2 were about 0.5. In the coupled channel analysis, the predicted values of elastic scattering were much different from the results of optical model analyses by coupling to the inelastic channel, and the potential whose imaginary part was shallower than that given by the optical model analysis gave better fit. The value of β must be -0.5 for 39.6 and 34.7 MeV.