L. S. Danu

Heavy Cluster Knockout Reaction {sup 16}O({sup 12}C,2{sup 12}C){sup 4}He and the Nature of the {sup 12}C-{sup 12}C Interaction Potential

The heavy cluster knockout reaction (16)O((12)C,2(12)C)(4)He performed for the first time, reveals the true nature of the (12)C-(12)C interaction. The observed cross section is enhanced by almost 2 orders of magnitude over the conventional zero range distorted wave impulse approximation (DWIA) predictions. An attractive (12)C-(12)C optical potential, as obtained in the folding model, does not explain the enhanced cross section in the finite range (FR) DWIA framework. The inclusion of a hard core of fairly long range ∼3.65  fm explains the data. The present investigation of (16)O((12)C,2(12)C)(4)He along with the (12)C-(12)C elastic scattering also proves beyond doubt that the folding models deep attractive heavy ion potentials are unsuitable to describe the highly overlapping heavy ions. The application of FR-DWIA opens up new avenues to use the heavy core knockout for the detailed investigation of heavy as well as Borromean halo nuclei.

Fission fragment angular distributions in the {sup 9}Be + {sup 232}Th reaction

Fission fragment angular distributions have been measured for a {sup 9}Be + {sup 232}Th system at four different beam energies around the Coulomb barrier. The experimental results on fission fragment anisotropies have been compared with predictions of the standard statistical saddle-point model (SSPM) and the preequilibrium fission (PEQ) model including projectile ground-state spin. It is observed that both SSPM and the PEQ model fail to reproduce the experimental results, indicating that projectile breakup may affect the fission fragment anisotropies.

Effect Of N = 40 Shell Closure On Barrier Distributions In {sup 18}O+{sup 58,60}Ni Reactions

The quasi-elastic scattering measurements for {sup 18}O+{sup 58,62}Ni systems have been carried out at {theta}{sub lab} = 150 deg. around Coulomb barrier energies to investigate the effect of nuclear shell closure on the barrier distributions. The {sup 18}O+{sup 58}Ni system leads to N = 40 neutron shell closure and {sup 18}O+{sup 62}Ni system is having N = 44 in the compound system. It is observed that target 2{sup +} and 3{sup -}, projectile 2{sup +} inelastic and 2n-transfer couplings are required in coupled-channels fusion model (CCFULL) calculations to get good comparison with the experimental barrier distribution of {sup 18}O+{sup 62}Ni system, whereas projectile 2{sup +} inelastic state coupling is not required for {sup 18}O+{sup 58}Ni system. However, the low energy structure observed in the barrier distribution of {sup 18}O+{sup 58}Ni system is not reproduced by coupled-channels calculations. This suggests, a possible additional effect due to N = 40 shell closure in the compound system not accounted for in coupled-channels calculations.