SEMI-ANALYTICAL APPROACHES IN THE COULOMB BREAKUP OF LOOSELY BOUND NUCLEI

Abstract

Coulomb breakup reactions have been an important tool in unraveling the structure of the exotic systems. This thesis concerns the application of the theory of elastic Coulomb breakup of a projectile in the field of a target nucleus under the framework of finite range distorted wave Born approximation, to problems related to the structure and reactions of nuclei away from the line of stability. The analytic nature of this theory stems from the fact that pure Coulomb wave functions are used in the calculation and that the dynamics can be analytically evaluated. The present endeavour is divided into seven chapters and three appendices. Chapter 1 gives a brief introduction to the subject and presents a review of the experimental scenario. Chapter 2 presents a short discussion of some of the theories used to describe breakup reactions. In chapter 3, we investigate the breakdown of N = 8 magic number near the neutron drip line by calculating the parallel momentum distribution of the charged fragment in the Coulomb breakup of various Be isotopes (N = 5, 6, 7, 8, 9) on Au target at 100 MeV/u. In chapter 4, we extend our Coulomb breakup theory to include ‘deformation’ effects in the structure part and thereby extend the application of our fully finite range quantum mechanical theory of Coulomb breakup to medium mass nuclei. Several reaction observables, like the total cross section, relative energy spectra, parallel momentum distribution, angular i ii and energy-angular distributions have been calculated. Comparing the calculated cross sections with the available experimental data, an effort has also been made to put constraints on the large uncertainties in the one-neutron separation energy of 31Ne. In chapter 5, we have applied our Coulomb breakup theory as an indirect approach in nuclear astrophysics. We calculated the 14C(n, γ)15C radiative capture cross section and the associated reaction rate per mole as a function of temperature, by studying the Coulomb dissociation of 15C on Pb at 68 MeV/u. In chapter 6, analytic efforts in the direction of a post form breakup reaction theory with three charged particles in the final channel are considered. We have also calculated the breakup amplitude with two charged particles in the final channel, using our theory, and have shown that it can be put on a firmer theoretical footing. The summary, conclusions and future directions of our work are presented in chapter 7. Some mathematical details of the formalism and of the approximations are also given in various appendices.