Study of 11Be structure through β-delayed decays from polarized 11Li

Abstract The excited states in the light neutron-rich nucleus 11 Be have been studied through the β -delayed neutron- and γ -decays from spin-polarized 11 Li g.s. . The level scheme and decay scheme of 11 Be ∗ are established from the β – γ , β –n and β –n– γ coincidences, and the spins and parities for 7 levels in 11 Be are firmly assigned from the β -decay asymmetries measured in coincidence with the delayed radiations. The neutron-spectroscopic factors of the levels in 11 Be are also determined. Some of the levels show good accord with predictions by the anti-symmetrized molecular dynamics (AMD) theory, which predicts various types of 2 α -cluster states in the rotational bands and a single α -cluster state.