ASPECTS OF HEAVY ION REACTION ANALYSIS IN THE FRAMEWORK OF QUANTUM MECHANICAL FRAGMENTATION THEORY

Abstract

The static and dynamic properties of the atomic nucleus have been investigated from time to time by different models and theories. A single model can not explain all the properties of the nucleus. Therefore, nuclear models have been developed to overcome the limitations of earlier models and have become a fundamental part of the evolution of nuclear physics. This thesis presents a work to study the decay of heavyion- induced reactions based on the Dynamic Cluster-decay Model (DCM). The role of deformation, orientation, and shell structure in the decay of excited compound nuclei has been investigated. This model is established on Quantum Mechanical Fragmentation Theory (QMFT), which further explains fusion and fission. Nuclear dynamics in reaction processes such as complete fusion, incomplete fusion, and fusion-fission have been understood using this model. Several other essential features of QMFT have also been investigated to infer reaction dynamics. The importance of incident energy, entrance channel effects, angular momentum, Coulomb factor, deformations, and orientations have been investigated according to different decay channels. This model suggests several new predictions for future validation. The analysis is presented in eight chapters, each described below. Chapter 1 briefly introduces the origin of nuclear physics, the application of the theoretical model used, and the broad and diverse spectrum of various nuclear reaction processes. Furthermore, the details of quasi-fission, fusion-fission, equilibrium preequilibrium processes, and complete-incomplete fusion reactions are given, which ends with a discussion on the scope and objectives of the thesis. Chapter 2 illustrates the theoretical background of the DCM to estimate the different nuclear reactions like compound fusion, incomplete fusion, and fusion-fission. A concise explanation of some input parameters used in the methodology is given, followed by a description of the different components of the fragmentation potential, i.e., binding energies, Coulomb potential, proximity potential, and centrifugal potential. The DCM model is suitably elaborated by taking these input parameters into account. Chapter 3 briefly describes the complete and incomplete fusion of cluster-structured 12C projectile onto a 52Cr target. DCM calculations involving quadrupole deformation and optimal orientation are discussed in the work. Chapter 4 describes the investigation of three decay fragment configurations spherical, β2-deformed ‘hot-compact’, and β2-deformed ‘cold-elongated’ to study the effects of deformation and orientation in the decay dynamics of compound nuclei with mass ACN ∼200 such as 194Hg∗, 197Tl∗, 202Pb∗ and 210Rn∗ formed in the 16O-induced reaction. Further, the role of the entrance channel in the subsequent decay dynamics of 194Hg∗ formed in reactions: 12C+182W, 16O+178Hf and 40Ar+154Sm are examined. Chapter 5 presents the effects of different nuclear radius parameters on decay paths of compound nucleus 197Tl∗ using a β2-deformed configuration with DCM at above barrier energy Ec.m. ∼100 MeV. Relative changes in barrier properties such as interaction barrier and interaction radius are observed with changes in the radius parameter of the decay fragments. Chapter 6 deals with the decay analysis of compound nuclei such as 96Zr∗, 98Ru∗, 60Ni∗, and 62Zn∗ formed in 48Ca+48Ca, 34S+64Ni, 34S+26Mg, and 35Cl+27Al. The fusion excitation functions are calculated using two theoretical approaches, DCM and PACE4. DCM-based moment of inertia like sticking limit (IS) and non-sticking limit (INS) are used to probe the decay dynamics. Chapter 7 investigates complete and incomplete fusion in a reaction induced by weakly bound projectile 7Li onto a target 93Nb. The decay analysis is worked out using quadrupole deformations with hot-compact orientation criteria to scrutinize the comparative analysis among CF and ICF processes in the decay modes like evaporation residues and intermediate-mass fragments. Additionally, the decay path of the different clusters with the same mass and the different charges have been examined to check the decay cross-sections’ contribution. Finally, Chapter 8 comprises the overall summary/conclusion of the thesis with a brief future outlook.