Study of the Effects of Nuclear Structure and Relative Orientations in Heavy Ion Reactions

Abstract

Heavy ion reaction dynamics has been studied using the Dynamical Cluster-decay Model (DCM) of Gupta and collaborators. DCM have been applied to study the decay of hot and rotating compound systems (i.e. having angular momentum, l ≠ 0 and temperature, T ≠ 0). The DCM is a reformulation of Preformed Cluster-decay Model PCM for ground-state decays (i.e. l = 0 and T = 0). Both DCM and PCM are based on Quantum Mechanical Fragmentation Theory (QMFT), first proposed by Gupta and Collaborators at Frankfurt, and then extended at Chandigarh. In DCM, decay of excited compound nuclei is studied as a collective clusterization process for emissions of the light particles LPs (n, p, α) and γ-rays, as well as the intermediate mass fragments IMFs (with 2 < Z < 10 and 5≤A≤20) and the symmetric and near-symmetric mass fragments SF and nSF (20≤A≤A/2), in contrast to the statistical models in which each type of emission is treated on different footing. Another advantage of using the DCM is that the structure effect of compound nuclei (CN) can be addressed via the preformation probability of the fragments, an information missing in the statistical fission models. Keeping in mind the temperature-dependence of collective potential used in DCM, first the temperature-dependent binding energies are calculated, which is an important step in the study of the decay of excited compound systems. The DCM have been applied successfully to study the decay of light (48Cr*) and heavy (246Bk*) mass nuclear systems formed in different entrance channels at a number of centre-of-mass energies Ec.m.. The role of excitation energy, entrance channel effects together with the effects of deformations and orientations in the fusion-fission process have been investigated extensively. The calculated DCM cross-section for all possible decay paths are found to be in excellent comparison with the available experimental data. Moreover, the possible role of deformed and oriented nuclei in cluster radioactivity has been investigated using the PCM, besides the well established shell effects. For this purpose we have chosen only those cluster decays for which daughter is always spherical and doubly magic (N = 126, Z = 82) 208Pb. The effects of nuclear structure and deformation together with orientations are thus established both in (radioactive) nuclei and excited compound systems via their cluster decay studies.