Structure of 8B from elastic and inelastic 7Be+p scattering

TL;DR

This study investigates the resonant structure of the nucleus 8B through elastic and inelastic 7Be+p scattering experiments, identifying new low-lying resonances and comparing results with advanced theoretical models to enhance understanding of light weakly bound nuclei.

Contribution

The paper reports the first experimental observation of specific low-lying resonances in 8B and compares these findings with state-of-the-art theoretical models, advancing nuclear structure knowledge.

Findings

New resonances at 1.9, 2.5, and 3.3 MeV in 8B identified.

Spin-parity assignments of 0+, 2+, and 1+ made for these states.

Good agreement between experimental data and theoretical models.

Abstract

Motivation: Detailed experimental knowledge of the level structure of light weakly bound nuclei is necessary to guide the development of new theoretical approaches that combine nuclear structure with reaction dynamics. Purpose: The resonant structure of 8B is studied in this work. Method: Excitation functions for elastic and inelastic 7Be+p scattering were measured using a 7Be rare isotope beam. Excitation energies ranging between 1.6 and 3.4 MeV were investigated. An R-matrix analysis of the excitation functions was performed. Results: New low-lying resonances at 1.9, 2.5, and 3.3 MeV in 8B are reported with spin-parity assignment 0+, 2+, and 1+, respectively. Comparison to the Time Dependent Continuum Shell (TDCSM) model and ab initio no-core shell model/resonating-group method (NCSM/RGM) calculations is performed. This work is a more detailed analysis of the data first published as a Rapid Communication. [J.P. Mitchell, et al, Phys. Rev. C 82, 011601(R) (2010)] Conclusions: Identification of the 0+, 2+, 1+ states that were predicted by some models at relatively low energy but never observed experimentally is an important step toward understanding the structure of 8B. Their identification was aided by having both elastic and inelastic scattering data. Direct comparison of the cross sections and phase shifts predicted by the TDCSM and ab initio No Core Shell Model coupled with the resonating group method is of particular interest and provides a good test for these theoretical approaches.