A systematic study of neutron-hole strength in the N=81 nuclei Ba137, Ce139, Nd141, and Sm143 is reported. The single-neutron removal reactions (p,d) and (He3,α) were measured at energies of 23 and 34 MeV, respectively. Spectroscopic factors were extracted from measured cross sections through a distorted-wave Born approximation analysis and centroids of single-particle strength have been established. The change in these centroid energies as a function of proton number have been compared to calculations of the monopole shift for the s1/2 and h11/2 orbitals, where the majority of the strength has been observed. Significant fragmentation of strength was observed for the d and g7/2 orbitals, particularly for the latter orbital which is deeply bound, with summed strengths that indicate a significant amount lies outside of the measured excitation energy range.
Publication Source (Journal or Book title)
Physical Review C
Howard, A., Freeman, S., Sharp, D., Bloxham, T., Clark, J., Deibel, C., Kay, B., Parker, P., Schiffer, J., & Thomas, J. (2020). Neutron-hole strength in N=81 nuclei. Physical Review C, 101 (3) https://doi.org/10.1103/PhysRevC.101.034309