HELIUM CLUSTERING IN NEUTRON-RICH Be ISOTOPES

The experimental study of the helium decays of the Be-10 and Be-12 excited states was performed at TRIUMF, Vancouver, using the transfer reactions of the Li-9 beam on the LiF target and resonant particle spec-troscopy technique. Part of the results from the full dataset are presented here, for the He-4+He-6 (0(+); 1.8 MeV, 2(+)), He-6+He-6 (0(+); 1.8 MeV, 2(+)), and He-4+He-8 decays of the Be-10 and Be-12 excited states, respectively. The He-6+He-6 (1.8 MeV, 2(+)) decay channel was observed for the first time in the present experiment, while for the He-4+He-6 (1.8 MeV, 2(+)) decay channel, there was previously only one measurement available, which present results agree with. New highly excited states were observed in all decay channels studied. Although branching ratios and the spins of the states were not determined, important spectroscopic information is obtained and present results are in good agreement with the proposed a-Xn-a molecular struc-ture of these isotopes, based on the comparison with previously published results.