Quasielastic excitation function measurement has been carried out for the 4 He + 232 Th system at θ lab = 160 • with respect to the beam direction, to obtain a representation of the fusion-barrier distribution. Using the present data along with previously measured barrier distribution results on 12 C, 16 O, and 19 F + 232 Th systems, a systematic analysis has been carried out to investigate the role of target and/or projectile structures on fusion-barrier distribution. It is observed that for 4 He, 12 C, and 16 O + 232 Th reactions, the couplings due to target states only are required in coupled-channel fusion calculations to explain the experimental data, whereas for the 19 F + 232 Th system along with the coupling of target states, inelastic states of 19 F are also required to explain the experimental results on fusion-barrier distribution. The width of the barrier distribution shows interesting transition behavior when plotted with respect to the target-projectile charge product for the above systems.

No abstract

Mass distributions of the fragments in the fission of 206 Po and the N=126 neutron shell closed nucleus 210 Po have been measured. No significant deviation of mass distributions has been found between 206 Po and 210 Po, indicating the absence of shell correction at the saddle point in both the nuclei, contrary to the reported angular anisotropy and pre-scission neutron multiplicity results. This new result provides benchmark data to test the new fission dynamical models to study the effect of shell correction on the potential energy surface at saddle point.

No abstract

No abstract