High-spin analog resonances near theN=50neutron shell

Abstract

The $^{96}\mathrm{Zr}(^{3}\mathrm{He},d)^{97}\mathrm{Nb}$ and the $^{92}\mathrm{Mo}(^{3}\mathrm{He},d)^{93}\mathrm{Tc}$ reactions, investigated at, respectively, 39.0 and 28.5 MeV incident energies, were used to populate selectively high-spin analog resonances in $^{97}\mathrm{Nb}$ and $^{93}\mathrm{Tc}$. Angular distributions were measured for the ${d}_{\frac{3}{2}}$, ${g}_{\frac{7}{2}}$, and ${h}_{\frac{11}{2}}$ analog states of the low-lying levels in $^{97}\mathrm{Zr}$. A distorted-wave Born-approximation analysis of the data for these unbound levels (using Gamow functions as form factors) was carried out and spectroscopic strengths extracted. The $^{96}\mathrm{Zr}(^{3}\mathrm{He},dp)$ and $^{92}\mathrm{Mo}(^{3}\mathrm{He},dp)$ reactions were performed, respectively, at 37.5 and 30 MeV incident energies. The angular distributions of the emitted protons were measured in coincidence using method II of Litherland and Ferguson with 0\ifmmode^\circ\else\textdegree\fi{} detection of deuteron groups. Spins, population parameters, and proton branching ratios to the ground state and excited states of the targets were determined from the analysis of the angular correlation data. The position of the neutron threshold as compared with the excitation energies of the analog states in $^{97}\mathrm{Nb}$ and $^{93}\mathrm{Tc}$ is found to be an important parameter in the extraction of the structure information on core-excited components in the parent levels wave functions. Neutron particle-hole multiplets based on the $({d}_{\frac{5}{2}})_{n}^{}{}_{}{}^{\ensuremath{-}1}\ensuremath{\bigotimes}({h}_{\frac{11}{2}})_{n}^{}{}_{}{}^{+1}$ and $({d}_{\frac{5}{2}})_{n}^{}{}_{}{}^{\ensuremath{-}1}\ensuremath{\bigotimes}({g}_{\frac{7}{2}})_{n}^{}{}_{}{}^{+1}$ configurations are observed for the first time in $^{96}\mathrm{Zr}$ through the decay of the ${g}_{\frac{7}{2}}$ and ${h}_{\frac{11}{2}}$ analog resonances. The limitation of the present method due to the neutron threshold or to the energy resolution in the proton channel is discussed and compared with the results of inelastic resonant scattering through isobaric analog resonances.NUCLEAR REACTIONS $^{92}\mathrm{Mo}(^{3}\mathrm{He},d)$ $E=28.5$ MeV; measured $\ensuremath{\sigma}({E}_{d},\ensuremath{\theta})$, $\ensuremath{\theta}=20\ifmmode^\circ\else\textdegree\fi{},35\ifmmode^\circ\else\textdegree\fi{}$. $^{96}\mathrm{Zr}(^{3}\mathrm{He},d)$ $E=39.0$ MeV; measured $\ensuremath{\sigma}({E}_{d},\ensuremath{\theta})$. $^{92}\mathrm{Mo}(^{3}\mathrm{He},d\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{p})$ $E=30$ MeV, $^{96}\mathrm{Zr}(^{3}\mathrm{He},d\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{p})$ $E=37.5$ MeV; measured $\ensuremath{\sigma}({E}_{d},{E}_{p},{\ensuremath{\theta}}_{P})$. $^{93}\mathrm{Tc}$, $^{97}\mathrm{Nb}$ deduced IAS, $L$, $J$, $\ensuremath{\pi}$, $S$, ${\ensuremath{\Gamma}}_{p}$, ${\ensuremath{\Gamma}}_{{p}^{\ensuremath{'}}}$. DWBA analysis using Gamow functions as form factors. Magnetic analysis. Enriched targets.