Structure and three-body decay of 9Be resonances

The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying Be-9 resonances into one neutron and two a particles. We investigate the six resonances above the breakup threshold and below 6 MeV: 1/2(+/-), 3/2(+/-), and 5/2(+/-). The short-distance properties of each resonance are studied, and the different angular momentum and parity configurations of the Be-8 and He-5 two-body substructures are determined. We compute the branching ratio for sequential decay via the Be-8 ground state, which qualitatively is consistent with measurements. We extract the momentum distributions after decay directly into the three-body continuum from the large-distance asymptotic structures. The kinematically complete results are presented as Dalitz plots as well as projections on given neutron and a energy. The distributions are discussed and, in most cases, found to agree with available experimental data.