Disappearance of the hindrance ofE1-transition involving loosely bound nucleon

AlthoughE1-transition between levels below giant dipole resonance are almost always strongly hindered, there are several exceptions as observed in¹¹Be and¹³C. These fastE1-transitions are studied by adopting a simple “cutoff” model, in which the behavior of single particle wave functions only outside of the nucleus contribute. The results are compared with the particle-GDR coupling model. The reason why theE1-hindrance disappears is explained. We also investigate the direct capture of thermal neutron by⁴⁰Ca andN=82 nuclei, where similar situation is observed. Further, the implication of the direct capture in multiple neutron capture is discussed.