Triplet of kindred prompt-2p emitters in mass-8 proton-rich nuclei

TL;DR

This paper reports the discovery and analysis of a triplet of prompt 2-proton emitters in A=8 nuclei, revealing their structural similarities and decay characteristics through experimental observations and ab initio calculations.

Contribution

It identifies a new 8B state and demonstrates the triplet nature of prompt 2p emitters with detailed decay and structural analysis, advancing understanding of proton-rich nuclei.

Findings

The 8B state at 8.4 MeV decays via prompt 2p emission.

The three states have similar spatial wavefunctions with different spin and isospin couplings.

All three emitters have oblate shapes, decaying to prolate-shaped states.

Abstract

A triplet of kindred prompt-2p emitters in A=8 nuclei has been demonstrated. Two of these are the ground state of 8C and its isobaric analog state in 8B, both of which are analogs of the halo or thick-skinned nucleus 8He. The third member is the recently found fourth 1+ state in 8B. This new 8B state at E*=8.4 MeV was observed to decay to the ground state of 6Li by 2p emission. Momentum correlations between the decay products indicate that it is not a sequential 2p decay through a 7Be intermediate state, but indicative of prompt 2p emission with correlations similar to those of the other members of the triplet. Ab initio calculations with the symmetry-adapted nocore shell model indicate that these three states have very similar spatial wavefunctions, but with nucleons coupling to different spins, isospins, and isospin projections. The triplet of 2p emitters all have oblate shapes and by stripping two protons equatorially, decay to states which have prolate shapes.