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Abstract Lifetimes of excited states in$$^{162}$$ $_{}^{162}$ Dy were measured using the (n,n’$$\gamma $$ $\gamma$ ) reaction with the Doppler-Shift Attenuation Method (DSAM) at the University of Kentucky’s Accelerator Laboratory. A total of eighteen level lifetimes were obtained, including eleven negative-parity states, seven of which are new. These measurements significantly expand the experimental database of transition probabilities for negative-parity bands in the well-deformed rare earth region of nuclei. The extracted B(E1) and B(E2) values reveal enhanced interband E1 ($$10^{-3}$$ ${10}^{-3}$ or$$10^{-4}$$ ${10}^{-4}$ ) W.u. and E2 strengths (several W.u.) between negative- and positive parity bands, particularly for the KEquation missing<#comment/>bands decaying to the the K$$^{\pi }=2^+_{\gamma }$$ $_{}^{\pi }=2_{\gamma }^{+}$ band, consistent with signatures of octupole-quadrupole coupling. In contrast, the K$$^{\pi }=0^-_1$$ $_{}^{\pi }=0_1^{-}$ and K$$^{\pi }=1^-_3$$ $_{}^{\pi }=1_3^{-}$ bands, which exhibit strong E1 transitions to the ground state band, are indicative of octupole-vibrational excitations built on the deformed ground state. Comparison of transition rates with Alaga rules supports this interpretation and distinguishes collective excitations from likely quasi-particle states. These new results establish$$^{162}$$ $_{}^{162}$ Dy as the most extensively characterized rare-earth nucleus for negative parity lifetimes and provide critical experimental benchmarks for theoretical models. 

Abstract The low-lying structure of the well-deformed nucleus$$^{158}$$ $_{}^{158}$ Gd has been revisited to elucidate the nature of the low-lying states in$$^{158}$$ $_{}^{158}$ Gd. Earlier (p, t) studies identified numerous 0$$^+$$ $_{}^{+}$ states below 4.3 MeV, prompting questions about whether these states correspond to collective vibrations or shape coexistence. New and previously reported ($$n,n^\prime \gamma $$ $n,n^{\prime }\gamma$ ) measurements are combined, including$$\gamma $$ $\gamma$ -$$\gamma $$ $\gamma$ coincidences, excitation functions, and angular distributions, to extract lifetimes and transition probabilities for 44 excited states up to 2.7 MeV, including 32 previously unmeasured levels. Our results confirm or revise$$\gamma $$ $\gamma$ -ray placements and provide detailed transition strengths, revealing both weakly collective and strongly enhanced B(E2) and B(E1) transition probabilities. In particular, a tentative 0$$^+$$ $_{}^{+}$ state at 2437.8 keV exhibits a strong interband B(E2) transition, which may be a candidate for a possible two-phonon ($$\beta \beta $$ $\beta \beta$ ) excitation. Systematic comparisons with neighboring Gd isotopes, Hartree–Fock–Bogoliubov, and interacting-boson model predictions suggest that the first excited 0$$^+$$ $_{}^{+}$ state in$$^{158}$$ $_{}^{158}$ Gd is predicted to be a$$\beta $$ $\beta$ -vibration, although it is weakly collective. We also present results for lifetimes and transition probabilities for a number of negative parity states, including$$\hbox {K}^{\pi }=0^-,1^-,2^-$$ ${\text{K}}^{\pi }=0^{-},1^{-},2^{-}$ sequences, perhaps providing insight into octupole collectivity and the interplay between quadrupole and octupole vibrations in deformed nuclei. The systematic presence of low-lying negative-parity bands and their interband transition strengths suggest that$$^{158}$$ $_{}^{158}$ Gd’s potential energy surface may support both quadrupole and octupole vibrational modes, in agreement with microscopic calculations [1–3]. 

The low-lying structure of⁷⁴Ge has been studied with γ-ray detection following inelastic neutron scattering. From excitation function and angular distribution data, the levels and transitions have been characterized including level spins and lifetimes, branching ratios, and multipole mixing ratios. In addition, a number of levels found in the literature for⁷⁴Ge appear to be erroneously placed. Upon removal of these states from the level scheme, excellent agreement with large-scale shell-model calculations was obtained. 

γ-ray production cross sections have been deduced for reactions with incident neutrons having energies from 1.5 - 4.7 MeV. Similar measurements were made on a natural Ti sample to establish an absolute normalization. The resulting γ-ray production cross sections are compared to TENDL and TALYS calculations, as well as data from previous measurements. The models are found to describe the production cross sections for mostγrays observed from⁵⁴Mn and⁵⁴Fe rather well. 

The nuclear structure of the⁹⁸Zr nucleus was studied through theβ⁻decay of⁹⁸Y_g.s.at the TRIUMF-ISAC facility. The use of the 8π γ-ray spectrometer with its ancillary detectors SCEPTAR and PACES enabled γ-γ and γ-e⁻coincidence measurements as well as γ-γ angular correlations. The level spin assignments and transition mixing ratios obtained in this study were in good agreement with previous results. Furthermore, 12 previously unknown states in the low-energy region of⁹⁸Zr were identified, including the 0⁺₅and 0⁺₆levels at 2418 and 2749 keV, respectively. The 2⁺and I=1 natures for multiple newly observed and previously known (but not firmly assigned) states have been established. Additionally, the previously assumed pureE2 character of the 2⁺₂→ 2⁺₁367.8-keV transition was confirmed.