High-spin states of the N = 48 nucleus 90Mo have been studied using the 33 MeV 90Zr(3He, 3nγ) reaction. A previously unknown level structure above the 8+ isomer and several new lower-lying levels have been identified. The results are discussed in terms of shell-model calculations which allow four protons in the 2p12 and 1g92 subshells and two neutron holes in the 1f52, 2p32, 2p12, or 1g92 orbitals.

Low-lying states of 90Nb have been investigated using the 90Zr(3He, t) reaction at 43.4 MeV. In addition to the well-knownπ(P12) v (g92)−1and π(g92) v (g92)−1 particle-hole states, many other levels were observed. The angular distributions for the (g92)2 states are investigated using DWBA calculations using collective, OPEP, and independent tensor and spin-isospin potentials.

Levels in $^{106}\mathrm{Ag}$ have been studied using heavy-ion reactions. The experiments included $\ensuremath{\gamma}$-ray yields as a function of bombarding energy, $\ensuremath{\gamma}$-ray angular distributions, $\ensuremath{\gamma}$-ray linear polarizations, and three-detector $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements. The decay scheme includes four collective bands with low-lying bandheads. The energies, $\ensuremath{\gamma}$-ray mixing ratios, and branching ratios of states in these bands are shown to be in good agreement with the corresponding quantities calculated using a two-particles-plus-rotor model at a small, symmetric deformation ($\ensuremath{\delta}=0.12$). The Coriolis and recoil effects are explicitly included and a variable moment of inertia is used. The calculation also shows that the four bands have predominant configurations $\ensuremath{\nu}({d}_{\frac{5}{2}})\ensuremath{\bigotimes}\ensuremath{\pi}({g}_{\frac{9}{2}})$, $\ensuremath{\nu}({g}_{\frac{7}{2}})\ensuremath{\bigotimes}\ensuremath{\pi}({g}_{\frac{9}{2}})$, $\ensuremath{\nu}({h}_{\frac{11}{2}})\ensuremath{\bigotimes}\ensuremath{\pi}({p}_{\frac{1}{2}})$, and $\ensuremath{\nu}({h}_{\frac{11}{2}})\ensuremath{\bigotimes}\ensuremath{\pi}({g}_{\frac{9}{2}})$, respectively. The $\ensuremath{\Delta}I=1$ and $\ensuremath{\Delta}I=2$ level sequences in the bands can be understood on the basis of the positions of the neutron and proton Fermi surfaces in the respective Nilsson bases. Another band observed experimentally on a ${10}^{\ensuremath{-}}$ bandhead at 2.4416 MeV is thought to have a four-quasiparticle structure.NUCLEAR STRUCTURE $^{96}\mathrm{Zr}(^{14}\mathrm{N},4n)^{106}\mathrm{Ag}$ at 49 MeV: measured ${I}_{\ensuremath{\gamma}}[E(^{14}\mathrm{N})]$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta})$, ${P}_{\ensuremath{\gamma}}$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin., $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ DCOQ. $^{106}\mathrm{Ag}$ deduced levels, $J$, $\ensuremath{\pi}$, $\ensuremath{\gamma}$ mixing ratios. Two-particle-plus-rotor calculations, Coriolis. Calculated levels, mixing ratios, branching ratios, lifetimes. Ge(Li) detectors.

A technique is presented for identifying γ rays from specific (particle, xnγ) reactions by measuring the time-of-flight of the outgoing neutrons. Gamma rays associated with different neutron multiplicities are shown to be coincident with different parts of the neutron time-of-flight spectrum.

Levels in $^{106}\mathrm{Cd}$ were studied using (heavy-ion, $\mathrm{xn}\ensuremath{\gamma}$) reactions. The experiments included $\ensuremath{\gamma}$-ray yields as a function of bombarding energy, $\ensuremath{\gamma}$-ray angular distributions, $\ensuremath{\gamma}$-ray linear polarizations, and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements. The decay scheme, which includes 85 $\ensuremath{\gamma}$-ray transitions, is similar to those reported for $^{108}\mathrm{Cd}$ and $^{102,104,106}\mathrm{Pd}$. In addition to the ground-state band, there appear two negative-parity collective bands built on two quasineutron states. The yrast positive-parity states appear dominated by intruder states at ${8}^{+}$, 3044.23 keV (two-quasiproton), ${10}^{+}$, 4435.08 keV (two-quasineutron), and ${12}^{+}$, 4659.81 keV (four-quasiparticle). The results are compared to calculations from a two-quasiparticle plus slightly deformed rotor model which utilizes a variable moment of inertia.NUCLEAR STRUCTURE $^{96}\mathrm{Mo}$($^{13}\mathrm{C}$,$3n\ensuremath{\gamma}$) at 45 MeV; $^{97}\mathrm{Mo}$($^{12}\mathrm{C}$,$3n\ensuremath{\gamma}$) at 45 MeV, $^{94}\mathrm{Zr}$($^{16}\mathrm{O}$,$4n\ensuremath{\gamma}$) at 63 MeV: measured ${I}_{\ensuremath{\gamma}}(E(^{13}\mathrm{C}))$, ${I}_{\ensuremath{\gamma}}(E(^{16}\mathrm{O}))$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta})^{13}\mathrm{C}$, $^{16}\mathrm{O}$, ${P}_{\ensuremath{\gamma}}[^{16}\mathrm{O}]$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin [$^{12}\mathrm{C}$, $^{16}\mathrm{O}$], $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ DCO [$^{12}\mathrm{C}$]. $^{106}\mathrm{Cd}$ deduced levels, $J$,$\ensuremath{\pi}$,$\ensuremath{\gamma}$ multipolarity. Rotational model calculations. Enriched targets, Ge(Li) detectors.

High-spin states in 91Nb populated by the 89Y(α, 2nγ) reaction were studied at 24.0 MeV and 35.7 MeV incident α-particle energy. Gamma-gamma coincidence and γ-ray angular distribution measurements were made. Several high-spin states in 91Nb were observed at 35.7 MeV bombarding energy which were not observable at 24.0 MeV. The shell model structure of these states is discussed.

Levels in $^{105,107}\mathrm{Ag}$ have been studied using heavy-ion reactions. The experiments included $\ensuremath{\gamma}$-ray yields as a function of bombarding energy, $\ensuremath{\gamma}$-ray angular distributions, and three-detector $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements. The positive-parity band based on the unique-parity ${g}_{\frac{9}{2}}$ orbital in both nuclei exhibits a $\ensuremath{\Delta}I=1$ character, unlike its counterpart ${h}_{\frac{11}{2}}$ band in Pd nuclei. The energy levels, $\ensuremath{\gamma}$-ray mixing ratios, branching ratios, and lifetimes in this band as well as in the ground-state negative-parity band are shown to be in good agreement with calculations using a particle-plus-rotor model at a small, symmetric deformation ($\ensuremath{\delta}=0.12$). The Coriolis and recoil effects are explicitly included and a variable moment of inertia is used. The low-lying "anomalous" $\frac{7}{{2}^{+}}$ state is also readily reproduced by this model. The calculation also shows that the $\ensuremath{\Delta}I=1$ nature of the positive-parity band results primarily from the fact that the Fermi surface is far from the $K=\frac{1}{2}$ state, whereas the transition properties are governed by the Coriolis mixing of the strong-coupled bands. Two bands built on the $\frac{17}{{2}^{\ensuremath{-}}}$ and $\frac{21}{{2}^{+}}$ states with high bandhead energies are thought to have three-quasiparticle configurations.NUCLEAR STRUCTURE $^{92}\mathrm{Zr}$($^{16}\mathrm{O}$,$p2n$)$^{105}\mathrm{Ag}$ at 60 MeV, $^{96}\mathrm{Zr}$($^{14}\mathrm{N}$, $3n$)$^{107}\mathrm{Ag}$ at 49 MeV: measured ${I}_{\ensuremath{\gamma}}(E(^{16}\mathrm{O}))$, ${I}_{\ensuremath{\gamma}}(E(^{14}\mathrm{N}))$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta})$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ DCOQ. $^{105,107}\mathrm{Ag}$ deduced levels, $J$, $\ensuremath{\pi}$, $\ensuremath{\gamma}$ mixing ratios. Rotational model calculations, Coriolis, calculated levels, mixing ratios, branching ratios, lifetimes. Ge(Li) detectors.

Levels in 108Cd were studied using the reaction 96Zr(16O, 4nγ)108Cd with a bombarding energy of 56 MeV. The experiments included γ-ray yields as a function of bombarding energy, γ-ray angular distributions, γ-ray linear polarizations and γ-γ coincidence measurements. The decay scheme which includes 48 γ-ray transitions is very similar to those reported for even-even Pd isotopes. In addition to the ground-state band, there appear to be four collective bands built on two-quasiparticle states. The results are in excellent agreement with a slightly deformed rotor description of the 108Cd nucleus.

Excited states in $^{105}\mathrm{Pd}$ have been populated using the reaction $^{96}\mathrm{Zr}(^{12}\mathrm{C}, 3n\ensuremath{\gamma})^{105}\mathrm{Pd}$. A new multiple-detector coincidence technique has resulted in greatly improved $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence statistics. Aligned members of particlecore multiplets observed formed $\ensuremath{\Delta}I=2$ bands built on $\frac{11}{{2}^{\ensuremath{-}}}$ and $\frac{7}{{2}^{+}}$ states. Many other nonaligned members of multiplets were observed as well. A $\ensuremath{\Delta}I=1$ band built on the $\frac{5}{{2}^{+}}$ ground state was also observed which has no counterpart in lighter Pd nuclei. All of these states have been successfully described by a general rotational model which assumes that $^{105}\mathrm{Pd}$ is a slightly deformed nucleus. The model includes a full treatment of Coriolis effects and a variable moment of inertia.NUCLEAR STRUCTURE $^{96}\mathrm{Zr}(^{12}\mathrm{C}, 3n\ensuremath{\gamma})$, $E=45$ MeV; measured ${I}_{\ensuremath{\gamma}}[E(^{12}\mathrm{C})]$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta})$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$-direct. corr., oriented nucl. $^{105}\mathrm{Pd}$ deduced levels, $J$,$\ensuremath{\pi}$, $\ensuremath{\gamma}$ multipolarity. Compared with rotational model.