This work focuses on the lifetime measurement and spectroscopic properties of 182W. The mass region around this nucleus is of significant interest due to its unexplored nature and the presence of intriguing structural phenomena, including deformation, shape changes, and shape coexistence. Experimental measurements were conducted in the National Laboratory IFIN-HH in Romania, focused on the spectroscopic study of 182W isotope using the Differential Decay Curve Method (DDCM), a similar approach for the Recoil Distance Doppler Shift (RDDS) method. This experiment provided valuable data on the energy levels, lifetimes, and decay properties of the excited states in the 182W and neighboring nuclei. The measurements were performed using the ROSPHERE detector array, loaded with HPGe and particle identification detectors, and a plunger device. As a result, the lifetime for the 61+ in 182W obtained for the first time via the fusion evaporation reaction 181Ta(11B, 10Be)182W and the DDCM at 47 MeV, and was found to agree well with earlier measurements.

The structure of the lowest-lying positive-parity states in Rh-99 was studied via in-beam fast-timing measurements performed with the hybrid RoSphere multidetector array. The half-life T-1/2 = 405 (20) ps, obtained for the 7/2(1)(+) state, suggests that the M1 component of the 7/2(1)(+) -> 9/2(1)(+) transition is hindered with respect to the single-particle estimates by two orders of magnitude, while the E2 component is enhanced, similarly to other odd-A nuclei in this region.

The excited states of neutron-rich Fe isotopes have been studied through a multinucleon transfer reaction of a Zn-70 beam on a U-238 target. Unambiguous identification of prompt gamma rays belonging to each nucleus was performed by coincidence detection of the ions in a high-acceptance magnetic spectrometer. The observed spectra are compared with large-scale shell-model calculations in the fpgd model space.

A study of the N = 81 odd-odd nucleus 140Pr with the 142Nd(d, alpha) reaction at 18-MeV incident energy is presented. A distorted-wave Born approximation analysis of measured angular distributions has been performed for 23 excited states up to Ex = 1.35 MeV, yielding information on the spin, parity, and sometimes on the simple proton-neutron structure of these states. The observed structure is discussed in comparison with that of other N = 81 isotones, from 136Cs to 144Eu, and with shell-odel calculations.

More than 200 states up to 4.1 MeV excitation have been populated in 168Er with the 170Er(p, t) reaction at 25 MeV incident energy. About 80 of these states, with 0+ and 2+ assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)]. The present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between 0+ and 7- are newly assigned for more than 100 states. For the states already reported in the ENSDF database with J & pi; values there is a good agreement with our values. The 168Er nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.

More than 200 states up to 4.1 MeV excitation have been populated in $^{168}\mathrm{Er}$ with the $^{170}\mathrm{Er}(p,t)$ reaction at 25 MeV incident energy. About 80 of these states, with ${0}^{+}$ and ${2}^{+}$ assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)]. The present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between ${0}^{+}$ and ${7}^{\ensuremath{-}}$ are newly assigned for more than 100 states. For the states already reported in the ENSDF database with ${J}^{\ensuremath{\pi}}$ values there is a good agreement with our values. The $^{168}\mathrm{Er}$ nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.

The odd-mass Pd99-105 nuclei were studied via Zr90-96((12)'C-13, xn gamma) fusion/evaporation reactions. The beam was provided by the IFIN-HH Tandem accelerator at energies of approximately 50 MeV. Emitted gamma rays were detected by the hybrid multidetector system RoSphere. The structure of the low-lying excited states in Pd99-105 and their gamma-decay pattern are discussed in the framework of the rigid triaxial rotor plus particle model, providing a reasonable description of the low-lying level energies, electromagnetic transition rates, and magnetic moments.

The medium-to-heavy mass ytterbium isotopes (70Yb) in the rare-earth mass region are known to be well-deformed nuclei, which can be populated to very high spin, and are predicted to exhibit interesting phenomena, such as shape coexistence. The lack of any experimental information on the structure of the neutron-rich 180Yb isotope and the lifetime of the 21+ state of 178Yb have greatly motivated this study, which can offer useful information for the collective behavior of neutrons and protons in neutron-rich Yb isotopes. A measurement was performed to investigate the population of excited states and a first measurement of the unknown 21+ lifetime of 178Yb by means of a two neutron-transfer reaction 176Yb(18O,16O)178Yb at energies 68-74 MeV using the ROSPHERE array at IFIN-HH, Romania.

The assignment of the first 2(+) state in Ga-62 has long been debated, due to its implications in triplet energy difference systematics in this mass region. An experiment has been performed at the IFIN-HH 9-MV Tandem accelerator using the ROSPHERE array in a mixed configuration of LaBr3(Ce) and HPGe detectors, as well as an additional array of liquid scintillator neutron detectors. Excited states in 62Ga were populated through a 2n fusion-evaporation channel and an anisotropy ratio was obtained from neutron-filtered HPGe statistics of transitions observed at different angles. A 2(+) state has been confirmed at an excitation energy of 978.1(1) keV. Theoretically, the interplay between isospin-symmetry breaking and shape-coexistence effects in the A = 62 isovector triplet is self-consistently treated within the beyond-mean-field complex excited Vampir variational model with symmetry projection before variation using an effective interaction obtained from a G matrix based on the charge-dependent Bonn CD potential adding the Coulomb interaction between the valence protons. Results are presented on Coulomb energy differences, mirror energy differences, triplet energy differences, and the superallowed Fermi beta decay of the ground state of Ge-62 and Ga-62.

The gyromagnetic factor of the low-lying ${E}_{x}=684.10(19)\phantom{\rule{4pt}{0ex}}\mathrm{keV}$ isomeric state of the nucleus $^{99}\mathrm{Mo}$ was measured using the time-dependent perturbed angular distribution technique. This level is assigned a spin and parity of ${J}^{\ensuremath{\pi}}=11/{2}^{\ensuremath{-}}$, with a half-life of ${T}_{1/2}=742(13)\phantom{\rule{0.16em}{0ex}}\mathrm{ns}$. The state of interest was populated and spin-aligned via a single-neutron transfer on a highly enriched $^{98}\mathrm{Mo}$ target. A magnetic moment ${\ensuremath{\mu}}_{\mathrm{expt}.}=\ensuremath{-}0.627(20){\ensuremath{\mu}}_{\mathrm{N}}$ was obtained. This result is far from the Schmidt value expected for a pure single-particle $\ensuremath{\nu}{h}_{11/2}$ state. A comparison of experimental spectroscopic properties of this nucleus is made with results of multishell Interacting boson-fermion Model (IBFM-1) calculations. In this approach, the ${J}^{\ensuremath{\pi}}=11/{2}^{\ensuremath{-}}$ isomeric state in $^{99}\mathrm{Mo}$ has a pure $\ensuremath{\nu}{h}_{11/2}$ configuration. Its magnetic moment, as well as that of other two excited states could be reasonably well reproduced by reducing the free neutron spin $g$ factor with a quenching factor of 0.45. This low value is not appropriate only for this case, similar values for the quenching factor being also required in order to describe magnetic moments in other nuclei from the same mass region.

The gyromagnetic factor of the low-lying E-x = 684.10(19) keV isomeric state of the nucleus Mo-99 was measured using the time-dependent perturbed angular distribution technique. This level is assigned a spin and parity of J(pi) = 11/2(-), with a half-life of T-1/2 = 742(13) ns. The state of interest was populated and spin-aligned via a single-neutron transfer on a highly enriched Mo-98 target. A magnetic moment mu(expt.) = -0.627(20)mu(N) was obtained. This result is far from the Schmidt value expected for a pure single-particle nu h(11/2) state. A comparison of experimental spectroscopic properties of this nucleus is made with results of multishell Interacting boson-fermion Model (IBFM-1) calculations. In this approach, the J(pi) = 11/2(-) isomeric state in Mo-99 has a pure nu h(11/2) configuration. Its magnetic moment, as well as that of other two excited states could be reasonably well reproduced by reducing the free neutron spin g factor with a quenching factor of 0.45. This low value is not appropriate only for this case, similar values for the quenching factor being also required in order to describe magnetic moments in other nuclei from the same mass region.

Rotational bands built on single quasiproton excitations in Cs-127 have been investigated using the Sb-121(C-12, alpha 2n) reaction and the ROSPHERE detector array at IFIN-HH, Bucharest. The lifetimes in the yrast negative-parity band based on the proton in h11/2 orbital have been measured by applying the Doppler-shift attenuation method. The lifetime of the 7/2+ 273-keV state, member of the rotational band associated with the proton g(7/2) orbital, has been determined as tau = 1.22(5) ns by the fast timing technique. The experimental data were compared with the calculations performed using the quasiparticle plus triaxial rotor model and deformation parameters epsilon(2) and gamma have been derived for the positive-and negative-parity structures. Evidence for triaxial nuclear shapes in the states described by the proton h(11/2) orbital was provided by both signature splitting and B(E2, Delta J = 2) transition strengths.

Lifetimes of the low-energy levels in Nd-136, populated in the reaction Te-124 (O-16, 4n), were measured with the ROSPHERE array at the Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), Bucharest-Magurele. The data were analyzed using the recoil distance Doppler shift method, and, in the cases where lifetimes were tau <= 1 ps, Doppler attenuation effects were taken into account. The deduced electromagnetic transition probabilities are discussed in the framework of the five-dimensional collective Hamiltonian (5DCH) theoretical model implemented with the D1S Gogny force, and detailed systematics of several observables in the even-even Nd isotopic chain are presented that highlight the transitional character of the neutron-deficient Nd isotopes. The 5DCH predictions are in overall good agreement with the present experimental results.

The level structure of $^{130}\mathrm{La}$ has been investigated using the $^{121}\mathrm{Sb}(^{12}\mathrm{C}$, 3n) reaction with the ROSPHERE array at IFIN-HH, Bucharest. The level scheme was significantly extended with the observation of 45 new states and 100 new transitions. Several band structures have been identified and a clear connection with the lower-lying states has been established. A lifetime of $\ensuremath{\tau}=3.6(2)$ ns has been measured for the 346-keV ${6}^{\ensuremath{-}}$ state by the in-beam fast timing technique. The lifetimes of 18 high-spin states have been determined by applying the Doppler-shift attenuation method. The deformations derived from the experimental $B(E2)$ transition strengths indicate distinct coexisting shapes at high spins in $^{130}\mathrm{La}$. The experimental properties of both low- and high-spin states were compared with theoretical calculations performed in the frame of the two-quasiparticles-plus-rotor model. Two new negative-parity decoupled bands, with a deduced quadrupole deformation ${\ensuremath{\beta}}_{2}=0.150(15)$, were interpreted by coupling the proton in the 1/2[550] and 3/2[541] orbitals with the odd neutron occupying mainly the low-$\mathrm{\ensuremath{\Omega}}$ orbitals from the ${d}_{3/2}$ and ${s}_{1/2}$ states. A quadrupole deformation ${\ensuremath{\beta}}_{2}=0.220(17)$ was derived for a newly identified positive-parity decoupled band. This enhanced deformation was attributed to the involvement in the band configuration of the $\mathrm{\ensuremath{\Omega}}=1/2$ $({f}_{7/2},{h}_{9/2})$ intruder neutron orbital. The multiparticle configuration $\ensuremath{\pi}{g}_{7/2}{({h}_{11/2})}^{2}\ensuremath{\bigotimes}\ensuremath{\nu}({h}_{11/2})$ was assigned to a high-spin negative-parity dipole band, based on the comparison of the experimental $B(M1)$ transition strengths with values calculated by applying the geometrical model of D\"onau and Frauendorf.

The $^{86}\mathrm{Zr}$ nucleus, which has a low-lying level scheme characteristic of a transitional nucleus, presents, according to the existing electromagnetic transition data, a subunitary ${\mathrm{B}}_{4/2}=B(E2,{4}_{1}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})/B(E2,{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ ratio, which is anomalously low for a nonmagic nucleus, as it is outside the range of the traditional collective models values. In order to check this anomaly, we performed new measurements of the lifetimes of its low-lying states, with the $\ensuremath{\gamma}$-ray coincident recoil distance Doppler shift method, using the ROSPHERE detector array. New lifetimes were determined for the positive-parity yrast states up to the ${10}^{+}$ one, and for the ${8}_{2}^{+},\phantom{\rule{0.16em}{0ex}}{5}_{1}^{\ensuremath{-}}$, and ${7}_{1}^{\ensuremath{-}}$ states. The newly determined values of the $B(E2)$ values for the ${2}_{1}^{+}$ and ${4}_{1}^{+}$ states characterize a nucleus with a moderate quadrupole deformation and are well described by the interacting boson model. The ratio ${B}_{4/2}=1.38(22)$ is no longer anomalous. The low $B(E2)$ value of the ${6}_{1}^{+}$ state indicates a noncollective structure.

The excitation spectra in the deformed nucleus 158Gd have been studied with high energy resolution by means of the (p,t) reaction using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for more than 200 excited states seen in the triton spectra up to 4.3 MeV. A number of 36 excited 0+ states (five tentative), have been assigned by comparison of experimental angular distributions with the calculated ones using the CHUCK code. Assignments for levels with higher spins are the following: 95 for 2+ states, 64 for 4+ states, 14 for 6+ states and about 20 for negative parity states. Sequences of states which can be treated as rotational bands are selected. The analysis of the moments of inertia defined for these bands is carried out. This high number of excited states in a deformed nucleus, close to a complete level scheme, constitutes a very good ground to check models of nuclear structure. The large ensembles of states with the same spin-parity offer unique opportunities for statistical analysis. Such an analysis for the 0+, 2+ and 4+ states sequences, for all K-values and for well-determined projections K of the angular momentum is performed. The obtained data may indicate on a K symmetry breaking. Experimental data are compared with interacting boson model (IBM) calculations using the spdf version of the model. The energies of the low-lying levels, the transition probabilities in the first bands and the distribution in transfer intensity of the 0+ states are calculated and compared with experiment.

The gyromagnetic factor of the low-lying E=251.96(9)  keV isomeric state of the nucleus ^{99}Zr was measured using the time-dependent perturbed angular distribution technique. This level is assigned a spin and parity of J^{π}=7/2^{+}, with a half-life of T_{1/2}=336(5)  ns. The isomer was produced and spin aligned via the abrasion-fission of a ^{238}U primary beam at RIKEN RIBF. A magnetic moment |μ|=2.31(14)μ_{N} was deduced showing that this isomer is not single particle in nature. A comparison of the experimental values with interacting boson-fermion model IBFM-1 results shows that this state is strongly mixed with a main νd_{5/2} composition. Furthermore, it was found that monopole single-particle evolution changes significantly with the appearance of collective modes, likely due to type-II shell evolution.

Excited states in the $^{158}\mathrm{Eu}$ nucleus have been determined with the $^{160}\mathrm{Gd}(d,\ensuremath{\alpha})^{158}\mathrm{Eu}$ reaction, studied at an incident energy of 18.0 MeV with the Munich tandem and Q3D spectrograph. More than 50 excited states have been determined up to 1.6 MeV excitation, some of them corresponding to states previously observed in the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{158}\mathrm{Sm}$. The number of levels found in this nucleus at low excitation energies follows the systematic trend of the level densities in the other isotopes with mass 152--156.