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

The excited states in the light neutron-rich nucleus 11Be have been studied through the β-delayed neutron- and γ-decays from spin-polarized11Lig.s.. The level scheme and decay scheme of 11Be∗ are established from the β-γ, β-n and β-n-γ coincidences, and the spins and parities for 7 levels in 11Be are firmly assigned from the β-decay asymmetries measured in coincidence with the delayed radiations. The neutron-spectroscopic factors of the levels in 11Be 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 2α-cluster states in the rotational bands and a single α-cluster state.