Single-Proton states of159Ho studied with the (p,α) reaction spectroscopic evidence for the unusual coriolis strengths in159, 161, 163Ho nuclei

The proton-hole character of states in159Ho has been studied using the162, 164Er(p, α)159, 161Ho reactions with 17 MeV protons. The shapes of angular distributions measured for both nuclei were compared, with good agreement in most cases, to tritoncluster-transfer DWBA calculations. The deviations obtained and the experimental normalization factors deduced for the164Er(p, α)161Ho reaction by comparisons to (t, α) cross sections indicate a need for a revised treatment of the mechanism of the (p, α) reaction on deformed nuclei. By comparisons to the well-known states in161Ho, nuclear structure factors were obtained for many levels in159Ho. The Nilsson assignments for the 3/2+[411], 5/2−[532] and 5/2+[413] bands were confirmed and the lowest rotational members of these bands were established. The anomalous strengths of the strongly mixed positive parity states in159, 161, 163Ho are discussed in the frame-work of the Nilsson model with the pairing and effective Coriolis strengths included. The Coriolis strengths giving best fits to excitation energies also improve the agreement of theory with the experimental nuclear structure factors. Rotational spacings of the 5/2+[413] and especially those of the 5/2−[532] bands in159, 161, 163Ho show mixmg effects unexplainable by the present calculations.