Nuclear-Structure Studies in Mo and Nb Isotopes via Stripping Reactions at 12 MeV

Abstract

Proton energy spectra from ($d,p$) reactions induced by 12-MeV deuterons on targets of ${\mathrm{Mo}}^{92}$, ${\mathrm{Mo}}^{94}$, ${\mathrm{Mo}}^{98}$, and ${\mathrm{Nb}}^{93}$ were measured with 7-9-keV resolution. Angular distributions of proton groups in the spectra were used to determine the $l$ values of the transitions yielding the respective proton groups. In reactions on the Mo isotopes, all of the expected strength is found for transitions leading to ${s}_{\frac{1}{2}}$, ${d}_{\frac{3}{2}}$, and ${d}_{\frac{5}{2}}$ states. In contrast with the situation in the isotonic Zr isotopes, where no ${h}_{\frac{11}{2}}$ states are known, one ${h}_{\frac{11}{2}}$ state is found in each odd-$A$ Mo isotope; however, in each case the excitation strength is only a small fraction of the expected total for that level. The total excitation strength for the ${g}_{\frac{7}{2}}$ level is also far below the expected total, and there is no evidence that this level is filling in the Mo isotopes as neutrons are added. In ${\mathrm{Nb}}^{94}$, values of $I$ for several members of the ($\ensuremath{\pi}{g}_{\frac{9}{2}}$) ($\ensuremath{\nu}{d}_{\frac{5}{2}}$) and ($\ensuremath{\pi}{g}_{\frac{9}{2}}$) ($\ensuremath{\nu}{g}_{\frac{7}{2}}$) configurations are estimated from sum rules and the presence of mixing.