Comparative study of the effect of resonances of the weakly bound nuclei Li6,7 on total fusion with light to heavy mass targets

Abstract

A systematic study of total fusion involving the weakly bound nuclei 6,7 Li with several light to heavy mass targets at Coulomb energies is presented. Emphasis is given to the role of resonance states (l = 2, J π = 3 + , 2 + , 1 + of 6 Li and l = 3, J π = 7/2 − , 5/2 − of 7 Li) on the total fusion excitation function. A comparative analysis of the effects of resonant breakup on total fusion is performed for both projectiles, using the Continuum-Discretized Coupled-Channel (CDCC) framework. The calculations demonstrate that (i) resonant breakup couplings play a more important role in total fusion than non-resonant couplings, (ii) resonance states with short half-lives are very important for total fusion, as incident energies decreases towards the Coulomb barrier energy where incomplete fusion dominates, and (iii) resonance states with long half-life act as quasi-bound inelastic states, playing a crucial role in complete fusion.

CDCC Calculations of Total Fusion of 6,7Li with Targets 27Al, 28Si, 144Sm, 198Pt, and 209Bi: Effect of Resonance States

“…The roles should be dependent on the decay time of the resonances relative to the typical collision time of interaction ~10 −21 s. The calculations are performed following the procedure as in Refs. [8][9][10]. That is, to calculate the effect of a resonance or group of resonance states, couplings to these states are omitted from the coupled-channel radial equations,…”

“…Resonance and non-resonance sub-spaces are those defined in Refs. [8][9][10]. The dashed-lines show the calculations when couplings to 2+ and 1+ and non-resonance states are considered but those from the 3+ resonance are omitted.…”

“…On the contrary, resonance states with smaller half-lives may break up as the projectile approaches the target, therefore, have a more important role on ICF. Excitation to non-resonance breakup states, due to their prompt breakup may have some contribution to ICF, but mostly feed elastic breakup states [10]. In this work, CDCC calculations of the effects resonance states of the weakly bound nuclei 6,7 Li in reaction with several targets at energies below and above the barrier energy are presented.…”

Application of the Lagrange-mesh method in continuum-discretized coupled-channel calculations

“…Although it is originally designed to describe deuteron-nucleus reactions [2][3][4], CDCC has succeeded in reproducing and analysing the scattering data of not only stable nuclei but also unstable nuclei, such as 6,7 Li [5-9], 7,11 Be [10][11][12], 8 B [13,14], 17 F [15,16], etc. Nowadays CDCC has been extensively applied in the studies of elastic scattering [2,4], polarization potential [17], breakup reaction [13], transfer reaction [18] and fusion reaction [7][8][9]11] for the weakly bound nuclei induced reactions. Some researches based on the CDCC framework for a further description of the reactions have been published, such as microscopic CDCC [5,19], four body CDCC [20,21], extended CDCC including the effect of core excitation [22,23] or target excitation [24].…”

Application of the Lagrange mesh method in continuum-discretized coupled-channels calculations

“…Although it is originally designed to describe deuteron-nucleus reactions [2], CDCC has been the most accurate and successful method to study the breakup reactions induced by heavy weakly bound nuclei, as it can provide a solution which is very close to the exact three-body wave function [3,4]. Nowadays CDCC has been extensively applied in the studies of elastic scattering [5,6], polarization potential [7], breakup reaction [8] and fusion reaction [9] for the nuclear reactions induced by weakly bound nuclei. Some researches based on CDCC framework for a further description of the reactions have been published, such as four body CDCC [10], extended CDCC including the effect of core excitation [11] or target excitation [12].…”