9Be: A gateway nucleus into heavier nuclei?

Abstract

Level structure of 9Be is investigated calculating poles of the alpha alphar n three-body scattering amplitude in the complex energy plane. We find 10 levels, which make rotational bands in both positive and negative parities. All of them, except 7/2^+, have been observed experimentally and the corresponding positions and widths reasonably well matched. The 7/2^+ has a large width, and therefore has not been found, but may cause a noise in the experiment. No other levels are needed to explain the existing experimental observables below 11.28 MeV, where the 9th excited state exists. We definitely assign it 9/2^-.