High-Resolution Study ofNb92by (d,t) and (d,tγ) Reactions

The reaction ${\mathrm{Nb}}^{93}\mathrm{}(d,t)\mathrm{}{\mathrm{Nb}}^{92}$ has been studied with a deuteron beam of 17 MeV. Reaction tritons were momentum-analyzed by the Enge split-pole spectrograph and detected by position-sensitive counters as well as nuclear emulsions placed along the focal plane of the spectrograph. The experimental energy resolution was ∼8 keV full width at half-maximum. Up to 3 MeV in excitation, approximately 50 states of ${\mathrm{Nb}}^{92}$ have been identified including the 6 previously known low-lying states. Angular distributions for 40 of these triton groups were obtained and $l$-transfer values for the neutron pickup to the corresponding states in ${\mathrm{Nb}}^{92}$ were assigned by comparison with distorted-wave calculations. A previous classification of the lowest six positive-parity states as belonging to the ($1g_{\frac{9}{2}}^{ \pi }2d_{\frac{5}{2}}^{ \nu }$) multiplet is confirmed. As there are ambiguities in the assignment of spins to some members of this multiplet on the basis of spectroscopic strengths alone, the electromagnetic-decay properties of the lowlying positive-parity states of ${\mathrm{Nb}}^{92}$ have been studied via the ${\mathrm{Nb}}^{93}(d,t\gamma ){\mathrm{Nb}}^{92}$ reaction. On the basis of the resulting decay scheme, spin assignments are made to the previously identified ($1g_{\frac{9}{2}}^{ \pi }2d_{\frac{5}{2}}^{ \nu }$) multiplet of states. The 286-, 357-, 480-, and 500-keV states are assigned $J^{\pi }$ values of $3^{+}$, $5^{+}$, $4^{+}$, and $6^{+}$, respectively.