RETARDATION OF SINGLE-PARTICLE E1 TRANSITIONS FROM THE 622 KEV BROAD D-WAVE NEUTRON RESONANCE IN BE-9

Capture gamma rays from the 622 keV d-wave neutron resonance in Be-9 w ith large reduced neutron width have been observed by means of a time- of-flight method, employing an anti-Compton NaI(Tl) detector. Partial radiative widths have been derived for the strong primary E1 transitio n to the 3368 keV (2+) state in Be-10 and also for the weak one to the 5958 keV (2+) state. Those widths were compared with predictions of t he Lane-Mughabghab valence-capture model. As a consequence we found ce rtain evidence to show that the 3368 keV state transition is appreciab ly hindered. The discrepancy can be removed by using a renormalized ne utron effective charge which takes into account the coupling between t he d-state neutron single-particle motion and the E1 giant resonance e xcitation of the target nucleus.