¹¹B states above the α-decay threshold via ¹⁰B(d,p)¹¹B

Interest in the resonance region surrounding ¹¹B has increased due to discrepancies in branching ratio calculations of β- delayed proton emission, a rare type of decay mode. Theoretical calculations predicted a significantly smaller ratio than observed in a recent experiment. However, the discovery of an 11.4 MeV state just above the proton threshold in ¹¹B through two recent experiments may explain the disagreement between theory and experiment.

To further study this region of interest, a neutron transfer reaction was performed using Florida State’s tandem Van de Graaff accelerator and Super Enge Split-pole Spectrometer. At least 6 states above the alpha-decay threshold of ¹¹B were observed. A strongly populated state at 11.25(1) MeV with a width of 108(12) keV was observed, and angular distributions were measured for the first time. DWBA calculations were performed to extract the spectroscopic factors for four of these states. The previously observed 11.4 MeV state was not observed. However, this is consistent with the fact that this state has a strong proton component, so we are unlikely to observe it in a neutron transfer reaction.