The nuclei ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{183,184}{}_{}{}^{}\mathrm{W}$ were studied with the ($n,\gamma$) reaction for neutrons of several resonant energies. High- and low-energy $\gamma$ radiation following resonant capture was observed with Ge(Li) detectors. Level schemes were constructed from these data in conjunction with previous information from charged-particle reactions and decay studies. Some discrepancies among previous studies were clarified and a large number of spin assignments suggested. From these and data from the ($d,p$) reaction an analysis is made of the fractionation and distribution of the single-particle Nilsson strength in the energy region 1.3-2.3 MeV. It is found that the Nilsson model breaks down rather suddenly above the vibrational energy: A much larger than expected number of rotational bands are observed and the ($d,p$) strength is severely fragmented. This mixing appears to be larger in ${}_{}{}^{183}{}_{}{}^{}\mathrm{W}$ than in ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$ and still larger in ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$. The data for $2^{+}$ and $1^{+}$ states in ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$ are compared with recent random-phase-approximation calculations: Again, much more configuration mixing is observed than is calculated and significant ($d,p$) strength occurs lower than predicted in the spectrum.

• Received 21 July 1972

DOI:https://doi.org/10.1103/PhysRevC.7.419