Systematic study on the role of various higher-order processes in the breakup of weakly-bound projectiles

Jagjit Singh, Takuma Matsumoto, Kazuyuki Ogata

Published 2020-05-12Version 1

Background: Breakup reactions are an efficient tool for studying the structure of weakly-bound neutron-rich and proton-rich exotic nuclei. The virtual photon theory (VPT), which is based on first-order Coulomb dissociation restricted to the electric dipole (E1), has been successfully used to explain the breakup data for several cases. Purpose: Our aim is to study the role of various higher-order processes that are ignored in the VPT, such as the nuclear breakup, interference between nuclear and Coulomb amplitudes, and multistep breakup processes mainly due to strong continuum-continuum couplings in the breakup of two-body projectiles on a heavy target at both intermediate and higher incident energies. Method: We employed quantum mechanical three-body continuum-discretized coupled-channels (CDCC) reaction model, which treats Coulomb and nuclear breakups, as well as their interference terms consistently on equal footing. Results: Our results for the breakup of $^{11}$Be, $^{31}$Ne, $^{8}$B, and $^{17}$F on $^{208}$Pb target at 100, 250, and 520 MeV/A, show the importance of nuclear breakup contribution, and its significant role in the multistep processes. Quantitatively, the multistep effects due to the nuclear breakup depend on the incident energy through the energy dependence of the core-target and nucleon-target nuclear potentials. The multistep effect on Coulomb breakup for core-neutron projectiles was found to be negligible, whereas it was important for core-proton projectiles. Coulomb-nuclear interference (CNI) effect was also found to be non-negligible. Conclusions: The nuclear breakup component, the CNI effect, and the multistep breakup processes are all found to be non-negligible; hence, the assumptions adopted in the VPT for the accurate description of breakup cross sections are not valid.