THE BETA-DECAY OF LI-9 TO LEVELS IN BE-9 - A NEW LOOK

Beta-delayed neutrons and alpha particles from the decay of 9Li have been studied with a 3He neutron spectrometer and silicon surface barrier detectors. The data show that the (50 ± 3)% feeding to particle unbound states mainly proceeds to the four excited states in 9Be at 2.43 MeV (30 ± 3)%, 2.78 MeV (16 ± 3)%, and 11.28 and 11.81 MeV (3.8 ± 0.2)%. The strong feeding to the 11.81 MeV state observed corresponds to a log ft value of 2.84. The beta-decay rates are strongly affected by the broad levels populated in the decay. Corrections involving R-matrix calculations have been applied for the extraction of the reduced transition probabilities. We confirm the recently determined strong asymmetry in the beta decays of the case3 2- ground states of 9C and 9Li to the excited case5 2- states in the daughters 9B and 9Be. © 1990.