Study of inclusive breakup reactions induced by weakly bound nuclei

Abstract

An important mechanism that takes place in the nuclear collisions is the dissociation of the projectile into two or more fragments. In many experiments, with both stable and radioactive nuclei, only one of the fragments is detected giving rise to the so-called inclusive breakup. For the two-body dissociation, this corresponds to reactions of the form a(b + x) + A ! b + anything. The theoretical interpretation of these reactions is complicated due to the fact that many processes (compound nucleus, transfer, direct breakup ...) can contribute to the production of the b fragment. The inclusive breakup is usually separated into two contributions, namely, the elastic breakup (EBU) and the nonelastic breakup (NEB). The former corresponds to processes in which the fragment b and x survive after the collisions and the target remains in its ground state. By contrast, nonelastic breakup corresponds to those breakup processes accompanied by the absorption of the unobserved fragment or by target excitation. The problem was addressed in the 1980s by several groups, who proposed closed-form formulae for the calculation of these observables. In this dissertation, we revisit the theory proposed by these groups, in particular, the theory of Ichimura, Austern, and Vincent (IAV) [Phys. Rev. C 32, 431 (1985)] and show applications to several reactions induced by weakly-bound projectiles, such as deuterons, 6;7Li, 7Be, 8B and 11Be, comparing with available data. In addition, we study the dependence of the EBU and NEB contributions with the incident energy and the separation energy of the projectile. We also investigate the reaction modes and reaction cross section of the 6Li + 209Bi reaction. We address the problem of the post-prior equivalence in inclusive breakup reactions. The problem is studied within the distorted-wave Born approximation (DWBA) version of IAV model. The post and prior formulas obtained in this model are briefly recalled and applied to several breakup reactions induced by deuterons and 6Li projectiles, to test their actual numerical equivalence. The different contributions of the prior-form formula are also discussed. A critical comparison with the prior-form DWBA model of Udagawa and Tamura [Phys. Rev. C 24, 1348 (1981)] is also provided. We also discuss the possibility of applying the IAV theory to the evaluation of incomplete fusion (ICF). For that, we propose a simple model and apply it to the 6Li+209Bi reaction. We also investigate the application of this model to the study of surrogate reactions, and illustrate it for the 238U(d; pf) reaction, comparing with recently measured data.