Continuum shell model calculations and the resonances below the GDR in12C

Abstract

The excitation functions in the11B(p, n0),11B(p, p1) and11B(p, γ) reaction channels predicted by a continuum shell model calculation are compared to facilitate isospin assignments forJ− resonances in the (19÷22) MeV region of excitation in12C. Model predictions are also tested against differential cross-section data in the particle channels. It is shown that definitive spin, isospin and parity assignments can be made for several dominant resonances reported in the literature. Comparison with recent (e, e′) data analysis not only confirms our model predictions but also demonstrates that level energies are well reproduced within the multiconfiguration shell model only if continuum effects are included.