Neutron decay widths of excited states of ¹¹Be.

The two-neutron transfer reaction 9Be(16O, 14O)11Be[10Be +n] has been used to measure the branching ratios for the neutron decay of excited states of 11Be. The 14O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the 10Be fragments of the decaying 11Be* recoil were measured in coincidence with the 14O ejectile using a double-sided silicon strip detector array at backward angles. This enabled a kinematic reconstruction of the reaction to be performed. Theoretical decay branch ratios were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the relative reduced widths of the states. The decay widths have been used to link states in 11Be with a common structure and structurally to states in the daughter nucleus 10Be. The 3/2- 8.82-MeV state was identified as a candidate for a molecular band head.