Importance of multi-step processes in the Coulomb and nuclear breakups of 15C halo nucleus

Abstract

Breakup reactions involving heavy targets are known to be dominated by the Coulomb breakup, and this is understood as due to the long-range nature of Coulomb forces and a large charge of the target nucleus. In this paper, we intended to find out whether these two factors alone can justify the large importance of the Coulomb breakup over its nuclear counterpart. To this end, we considered the [Formula: see text] breakup reaction at an incident energy of [Formula: see text]. By analyzing this reaction, it is found that the continuum–continuum couplings and higher-order multipole transitions, which are characteristic of nuclear reactions induced by loosely bound projectiles, strongly suppress the nuclear breakup cross-section and have a negligible effect on the Coulomb breakup cross-section. When these reaction dynamics are removed, the nuclear breakup cross-section becomes more important than the Coulomb breakup cross-section at large incident angles. In conclusion, these results infer that the predominance of the Coulomb breakup over the nuclear breakup in reactions involving heavy targets can be explained by three main factors: the large target charge and the long-range nature of Coulomb, as well as the prevailing reaction dynamics such as continuum–continuum couplings and higher-order multipole transitions. These results could motivate further improvements on the theoretical approaches used in pure Coulomb breakup calculations.