Breakup of the proton halo nucleus 8B near barrier energies

Abstract

The dynamics of a nuclear open quantum system could be revealed in the correlations between the breakup fragments of halo nuclei. The breakup mechanism of a proton halo nuclear system is of particular interest as the Coulomb polarization may play an important role, which, however, remains an open question. Here we use a highly efficient silicon detector array and measure the correlations between the breakup fragments of 8B incident on 120Sn at near-barrier energies. The energy and angular correlations can be explained by a fully quantum mechanical method based on the state-of-the-art continuum discretized coupled channel calculations. The results indicate that, compared to the neutron halo nucleus 6He, 8B presents distinctive reaction dynamics: the dominance of the elastic breakup. This breakup occurs mainly via the short-lived continuum states, almost exhausts the 7Be yield, indicating the effect of Coulomb polarization on the proton halo state. The correlation information reveals that the prompt breakup mechanism dominates, occurring predominantly on the outgoing trajectory. We also show that, as a large environment, the continuum of 8B breakup may not significantly influence elastic scattering and complete fusion.

Breakup dynamics of a neutron-halo projectile on heavy target at deep sub-barrier energies

“…A subsequent analysis in [11], of the same reaction with the 8 B proton-halo nucleus, within the same incident energy range, further confirmed the findings of [1], by indicating the effect of Coulomb polarization on the proton halo state, with the correlation information revealing that the prompt breakup mechanism dominates, occurring predominantly on the outgoing trajectory. This assertion corroborates the conclusion anticipated in [2] that the breakup of the projectile occurs in the outgoing trajectory.…”

“…Particularly, in [11], it was emphasized the relevance of elucidating the long-standing question about the breakup dynamics of a proton halo nucleus. Relying on the results obtained near Coulomb barrier energies, their analyses have signaled distinctive dynamics of a proton-halo nucleus as compared with a neutron-halo nucleus, which has been assigned to the Coulomb effect of the halo proton, indicating little influence of the continuum on elastic scattering and complete fusion.…”

“…Relying on the results obtained near Coulomb barrier energies, their analyses have signaled distinctive dynamics of a proton-halo nucleus as compared with a neutron-halo nucleus, which has been assigned to the Coulomb effect of the halo proton, indicating little influence of the continuum on elastic scattering and complete fusion. Nevertheless, as commented in [11], further investigations are still desired to elucidate the breakup behavior of a proton halo nuclear system, which can be quite relevant in the light of potential astrophysical implications. In this regard, one could check whether the conclusions reported in [1,2,11] can be assumed as a universal signature of the breakup of weakly-bound systems at deep sub-barrier energies, by first extending the same investigation to neutron-halo projectiles.…”

“…Nevertheless, as commented in [11], further investigations are still desired to elucidate the breakup behavior of a proton halo nuclear system, which can be quite relevant in the light of potential astrophysical implications. In this regard, one could check whether the conclusions reported in [1,2,11] can be assumed as a universal signature of the breakup of weakly-bound systems at deep sub-barrier energies, by first extending the same investigation to neutron-halo projectiles. The fundamental difference between protonhalo and neutron-halo is the presence of the Coulomb barrier in the core-proton system, which is absent in the core-neutron system since the neutron is not charged.…”

Systematic extraction of the strong absorption distance and Coulomb barrier from elastic scattering*

“…scatterings are less affected by other reaction channels, we propose obtaining from based on a simple transformation. (3) The extracted from elastic scattering is proportional to the Coulomb parameter z, which is close to that extracted from fusion reactions. We also find that exotic structures, such as large deformations, have little influence on this linear relationship.…”