The lifetimes of low-lying excited states below the 8+ seniority isomer were directly measured using fast timing detectors in the neutron-deficient isotopes 98,100Cd. This experiment was conducted with the DEcay SPECtroscopy (DESPEC) setup at GSI, where the ions of interest were produced via a fragmentation reaction and identified using the FRagment Separator (FRS) before being implanted in the AIDA active stopper system, and the γ rays emitted during the de-excitation of isomeric states were detected by the LaBr3 FATIMA Array. The newly deduced values for the reduced transition probabilities were compared with shell-model calculations using different interactions and effective charges. The results indicate that, while 98Cd aligns well with a seniority scheme description, in 100Cd the transition strengths among low-lying states are not fully reproduced, and the nature of these states remains an open problem within the present theoretical description. Ultimately, a key element in the description of this region, crucial for nuclear physics and astrophysics, appears to be the proton-neutron term of the nuclear effective interaction.

At a fundamental level, the interactions between protons and protons, protons and neutrons, and neutrons and neutrons are not identical. Such isospin nonconserving interactions emerge when comparing the excitation energy of analog states in T=1 triplet nuclei. Here, we extend such an analysis to the A=78, T=1 triplet system - the heaviest system for which such complete data exists - and find strong disagreement with contemporary theory. This was achieved by pioneering the technique of recoil-β-β tagging to identify excited states in Zr78. We also established a Zr78 half-life of 25-8+17 ms and extended the T=1 band in Y78 to Jπ=(10+).

Excited states ranging from low to high spin in Nd135 have been investigated using the Mo100(Ar40, 5n) heavy ion fusion evaporation reaction with the JUROGAM II γ-ray spectrometer. In the present work we report a new 17/23- state and a new band composed of E2 transitions at high spin. The configuration assigned to the 17/23- state is obtained by coupling one neutron in the 1/2+[400] orbital to the 8- isomer in Nd134 based on the ν7/2+[404] - 9/2-[514] configuration. The deduced ratio of reduced transition probabilities of 2.0(5) from the new 17/23- state to the 13/22- and 13/21- states supports the tilted precession interpretation of the band built on the 13/22- state, in which, instead of the rotation around the intermediate axis present in the yrast band, the rotation is around the long axis of the intrinsic reference frame. The configuration of the newly observed high-spin band is discussed in the framework of the cranked Nilsson-Strutinsky model. The calculated results provide evidence for large triaxiality of the discussed bands.

The very neutron-deficient strongly deformed 117Cs nucleus has been studied using the 58Ni(64Zn, 1 alpha 1p) reaction and JUROGAM 3 gamma -ray detector array coupled to the MARA recoil-mass separator. Three previously known and three newly identified rotational bands were observed up to very high spin and excitation energy. All bands are firmly assigned to 117Cs based on measured mass spectra and interconnecting transitions. The ground-state spin and parity are suggested based on the systematics of low-lying states in odd-even cesium nuclei. The systematics of bandheads in cesium nuclei reveal maximum collectivity and deformation is reached for neutron numbers 64-66, corresponding to the middle of the N = 50-82 magic shell. The rotational frequencies of the first and second crossings in the different bands are similar to those observed in the corresponding bands in the neighboring 119Cs nucleus, suggesting similar deformations of the two nuclei, but enhanced softness in 117Cs. Particle number conserving cranked shell model calculations describe the observed band structures well.

The neutron-rich rare isotope 190W is discussed as a candidate for a prolate-oblate transitional nucleus with maximum γ-softness. The collectivity of this isotope is assessed for the first time by the measurement of the reduced E2 transition probability of its first 2+ state to the ground state. The experiment employed the FAst TIming Array (FATIMA), comprised of 36 LaBr3(Ce) scintillators, which was part of the DESPEC setup at GSI, Darmstadt. The 41+ and 21+ states of 190W were populated subsequently to the decay of its 127(12) μs isomeric Jπ=10− state. The mean lifetime of the 21+ state was determined to be τ=274(28) ps, which corresponds to a B(E2;21+→01+) value of 95(10) W.u. The results motivated a revision of previous calculations within an energy-density functional-based interacting boson model-2 approach, yielding E2 transition properties and spectroscopic quadrupole moments for tungsten isotopes. From comparison to theory, the new data suggest that 190W is at the transition from prolate to oblate structure along the W isotopic chain, which had previously been discussed as a nuclear shape-phase transition.

Excited states have been observed for the first time in the very neutron-deficient odd-odd nucleus 57120La63. The observed γ rays have been assigned based on coincidences with lanthanum X rays measured with the JUROGAM 3 array and with A=120 fusion-evaporation residues measured with the MARA separator. The observed γ rays form a rotational band which decays to the ground state via a cascade of four low-energy transitions. Based on the systematic comparisons with the heavier odd-odd La isotopes we assign spin-parity 4+ to the ground state and a πh11/2⊗νh11/2 configuration to the rotational band. The nuclear shape has been investigated by the cranked Nilsson-Strutinsky model. Two quasiparticle plus triaxial rotor model calculations including the np interaction nicely reproduce the spin of the inversion between the even- and odd-spin cascades of E2 transitions, giving credit to the np interaction as an important parameter responsible for the mechanism inducing the inversion. The position of the Fermi levels, in particular for neutrons, also has a strong impact on the observed inversion in the chain of lanthanum nuclei.

We report on a study of the alpha-decay fine structure and the associated E alpha-E gamma correlations in the decays of 171,172Os and 171,172,174Ir. In total, 13 new alpha-decay energy lines have been resolved, and three new gamma-ray transitions have been observed following the new decay branches to 168Re and 167W. The weak alpha-decay branch from the bandhead of the nu i13/2 band in 171Os observed in this work highlights an unusual competition between alpha, beta, and electromagnetic decays from this isomeric state. The nucleus 171Os is therefore one of few nuclei observed to exhibit three different decay modes from the same excited state. The nuclei of interest were produced in 92Mo(83Kr, xpyn) fusion-evaporation reactions at the Accelerator Laboratory of the University of Jyvaskyla, Finland. The fusion products were selected using the gas-filled ion separator RITU and their decays were characterized using an array of detectors for charged particles and electromagnetic radiation known as GREAT. Prompt gamma-ray transitions were detected and correlated with the decays using the JUROGAM II germanium detector array surrounding the target position. Results obtained from total Routhian surface (TRS) calculations suggest that alpha-decay fine structure and the associated hindrance factors may be a sensitive probe of even relatively small shape changes between the final states in the daughter nucleus.

Three three-quasiparticle isomers, one at an excitation energy of 2.3 MeV with T1/2=0.48(4)μs, and two shorter-lived with unknown half-lives at slightly lower energies have been identified in Nd129 using the MARA + JUROGAM 3 setup and the recoil tagging technique. All three isomers present decay patterns characteristic of high-K isomers. The known 6.7 s β-decaying isomer previously assigned to the 5/2+ level is now assigned to the new 7/2- ground state. A new low-spin 5/2+ isomeric state with a half-life of a few tens of nanoseconds has been identified, while a previously known 2.6 s β-decay activity was assigned to the band head of the ν1/2+[411] band. The transitions depopulating the high-K isomers to low-lying states also establish the relative energies of three low-lying one-quasiparticle bands, leading to a new spin-parity assignment of 7/2- to the ground state of Nd129. The partial half-lives of the depopulating transitions suggest spin-parities 21/2+, 19/2+, and 17/2+ for the three high-K isomers. The properties of the band built on the 21/2+ isomeric state suggest a one neutron-two proton configuration. Based on the results of extensive calculations with different models, we also assign one neutron-two proton configurations to the 19/2+ and 17/2+ isomeric states. The assigned configurations of the 17/2+ and 21/2+ isomeric states involve the π9/2+[404] orbital, which is identified in three-quasiparticle bands of proton-rich A≈130 nuclei.

Two rotational hands are identified in Cs-119, one of which having very similar pattern to that of the strongly-coupled pi g(9/2)[404]9/2(+) band. The properties of the bands with similar patterns extracted from the experimental data are in agreement with a chiral interpretation. Tilted axis cranking covariant density functional theory with pairing correlations and particle-number conserving cranked shell model calculations are employed to determine the deformation and to investigate the band configurations, respectively. It results that the backbending is induced by the rotational alignment of two h(11/2 )protons, whose angular momenta reorient from the short to the intermediate axis, in a plane orthogonal to the angular momentum of the strongly-coupled g(9/2) proton which keeps aligned along the long axis. The total spin points in 3D, inducing the breaking of the chiral symmetry. This is the first observation of candidate chiral bands built on a configuration with three protons, one in the strongly coupled [404]9/2(+) orbital which does not change orientation with increasing rotational frequency, and two in the h(1)(1/)(2) orbital which reorients to the rotation axis. The bands are observed in the transient backbending regime, showing that the chirality in nuclei is a general phenomenon, being robust and present not only in nuclei with nearly maximal triaxiality and pure configurations, but also in nuclei with moderate triaxiality and mixed configurations which gradually evolve from one to three-quasiparticle configurations, like in the backbending region.

The electromagnetic character of the Delta I = 1 transitions connecting the 1- to 0-phonon and the 2- to 1-phonon wobbling bands should be dominated by an E2 component, due to the collective motion of the entire nuclear charge. In the present work it is shown, based on combined angular correlation and linear polarization measurements, that the mixing ratios of all analyzed connecting transitions between low-lying bands in Pr-135 interpreted as 0-, 1-, and 2-phonon wobbling bands, have absolute values smaller than one. This indicates predominant M1 magnetic character, which is incompatible with the proposed wobbling nature. All experimental observables are instead in good agreement with quasiparticle-plus-triaxial-rotor model calculations, which describe the bands as resulting from a rapid re-alignment of the total angular momentum from the short to the intermediate nuclear axis.