Neutron single-hole states in 149Sm, 157Gd and 196Au investigated by (p, d) reactions

Abstract

In order to continue studies of neutron single-hole states in nuclei of 50 ≦ N ≦ 126, (p, d) reactions on 150Sm, 158Gd and 197Au have been investigated by the use of a proton beam of 55 MeV. Emitted particles were analysed with a broad-range magnetic spectrometer and detected with a 200 proportional counter system. Angular distributions of 39 deuteron groups are analysed with the aid of the DWBA method. The l-values are assigned, and J π values and the spectroscopic factor for each state are obtained. Many new excited states have been found and their J π values are given. Energy shifts of the neutron single-hole states of 3p 1 2 ., 2f 5 2 , 3p 3 2 , li 13 2 , 2f 7 2 and 1h 9 2 observed between 207,205Pb and 196Au are interpreted on the basis of effective proton-neutron interactions. The observed energy shifts are reproduced rather well by the use of the interaction V pn = ( V 0 + V 1 σ p · σ n) δ(r p − r n) and of the harmonic-oscil except for the case of the p 1 2 state. In order to explain the shift of the p 1 2 state relative to the p 3 2 state, it is necessary to introduce some spin-dependent interactions such as tensor interactions and/or two-body spin-orbit interactions.