Resonance structure of 9Be and 10Be in a microscopic cluster model

Abstract

Structure of the excited states in 9Be and 10Be have been theoretically explored by means of the α+α+n and α+α+n+n microscopic cluster model respectively. Resonance excited states in 9Be and 10Be are localized by solving the two‐body scattering problems of {8Be(0+, 2+, 4+)+n, 5He(3/2−, 1/2−)+α} and {9Be(3/2−, 1/2+, 5/2−)+n, 6He(0+, 2+)+α} respectively. Our models have reproduced satisfactorily the experimental low‐energy spectrum in 9Be and given various resonance excited states in 10Be. Our model shows that the two and three competing configurations are quite essential to reproduce the anomalous 1/2+ state in 9Be and the second 0+ state in 10Be respectively. One of these configurations has a strong core(8Be) distortion which is induced by the valence neutron and is responsible for lowering the s1/2 orbit in these states. Another configuration produces a spatially extended neutron distribution outside the core like the neutron halo.