Background: The heaviest T-z = 0 doubly-magic nucleus, Sn-100, and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structure of light-Sn nuclei has been shown to be affected by the delicate balance between nuclear-interaction components, such as pairing and quadrupole correlations. From Cd to Te, many common features and phenomena have been observed experimentally along the isotopic chains, leading to theoretical studies devoted to a more general and comprehensive study of the region. In this context, having only two proton holes in the Z = 50 shell, the Cd isotopes are expected to present properties similar to those found in the Sn isotopic chain. Purpose: The aim of this work was to measure lifetimes of excited states in neutron-deficient nuclei in the vicinity of Sn-100. Methods: The neutron-deficient nuclei in the N approximate to Z approximate to 50 region were populated using a multinucleon transfer reaction with a Cd-106 beam and a Mo-92 target. The beamlike products were identified by the VAMOS++ spectrometer, while the gamma rays were detected using the AGATA array. Lifetimes of excited states were determined using the recoil distance Doppler-shift method, employing the Cologne differential plunger. Results: Lifetimes of low-lying states were measured in the even-mass Cd-102-(108) isotopes. In particular, multiple states with excitation energy up to MeV, belonging to various bands, were populated in approximate to 3 Cd-106 via inelastic scattering. The transition strengths corresponding to the measured lifetimes were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach. Conclusions: Despite the similarities in the electromagnetic properties of the low-lying states, there is a fundamental structural difference between the ground-state bands in the Z = 48 and Z = 50 isotopes. The comparison between experimental and theoretical results revealed a rotational character of the Cd nuclei, which have prolate-deformed ground states with beta(2) approximate to 0.2. At this deformation Z = 48 becomes a closed-shell configuration, which is favored with respect to the spherical one.

Fine structure in the alpha decay of Th-221(90) , populating excited states in( 88)(217)Ra, was studied using alpha gamma-coincidence spectroscopy. Two alpha-decay branches from Th-221 have been newly observed, with E-alpha(keV)[b(alpha)(%)] = 7951(8)[0.14(3)] and 8247(3)[1.51(12)], together with three previously known branches. Also, two new states in Ra-217 were identified at E = 177 and 227 keV. The ground-state configurations of the odd-A, N = 131 transitional isotones above Pb-208 are interpreted from their a-decay fine structure systematics and considered in terms of predictions using spherical shell and reflection-asymmetric models.

Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus Rh-95. The fusion-evaporation reaction Ni-58(Ca-40, 3p) was used to populate high-spin states in Rh-95 at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6 mg/cm(2) metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations. state-of-the-art theory. Remarkably, the structural features up to moderate angular momentum of nuclei immediately below the N = Z = 50 shell closures can be described with high accuracy in a very simple way by shell-model calculations including only the g(9/2) and p(1/2) subshells. Of special interest is the neutron-proton pair coupling scheme which is expected to appear in the heaviest N=Z nuclei [1,2] and the seniority structure of the N = 50 isotones [3-7]. However, multiple core-excited states have been observed in the semi-magic nuclei of the Sn-100 region [8-10]. The theoretical study of those states is a challenging task, which requires a significantly larger model space for their interpretation. Transition probabilities between nuclear states provide important constraints for theoretical modelling of the structure of the nuclei of interest. Our previous lifetime study of the semimagic (N = 50) nucleus Ru-94 [ 11,12] provided information on the electromagnetic decay properties of neutron-core excited states. We now address lifetime measurements in its closest, more neutron deficient, isotone Rh-95 using the same DSAM technique. The experimental results have been interpreted within the framework of large-scale shell-model (LSSM) calculations.

The lifetimes of the low-lying excited states 2(+) and 4(+) have been directly measured in the neutron-deficient Sn-106,Sn-108 isotopes. The nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. The emitted gamma rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2; 2(1)(+) -> 0(g.s)(+)) values and it describes well the experimental pattern for Sn104-114 ; the B(E2;(+)(4) -> 2(1)(+)) values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in Sn-108. 

A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10(+) state in Lu-156 has been discovered. The Lu-156 nuclei were produced by bombarding isotopically enriched Cd-106 targets with beams of Ni-58 ions, separated in flight using the gas-filled separator RITU and their decays were measured using the GREAT spectrometer. Analysis of the main decay path that populates yrast states observed previously suggests a spin-parity assignment of 19(-) for the isomeric state, which is consistent with isomeric states identified in the N = 85 isotones. Comparison with other decay paths in Lu-156 indicates that the [pi h(11/)(2)(-1) circle times nu h(9/2)]10(+) state at the bottom of the yrast sequence is likely to be the a-decaying isomeric state, with the [pi h(11/)(2)(-1) circle times nu f(7/2)]9(+) state lying 62 keV above it. The relative ordering of the lowest-lying 9(+) and 10(+) states is inverted in Lu-156 compared with its odd-odd isotones.

Fine structure in the a decay of high-spin isomers in Lu-155( 25/2(-)) and Hf-156(8(+))has been studied for the first time using alpha gamma- coincidence analysis. Three new a decays from Lu-155(25/2(-)) and two from Hf-156(8(+)) have been identified, populating seniority s > 1 states in the N = 82 nuclei Tm-151 and Yb-152, respectively. The reduced hindrance factors of the a decays support the previous configuration assignments of the populated states. This is the first observation of states with excitation energy greater than 1.5 MeV being populated following a decay in nuclei outside of the Pb-208 region.

Using fusion-evaporation reactions, a gas-filled recoil separator, recoil-gating technique and recoil-isomer decay tagging technique we have extended the level scheme of At-203 (N = 118) significantly. We have observed an isomeric [tau = 14.1(3) mu s] state with a spin and parity of 29/2(+). The isomeric state is suggested to originate from the pi(h(9/2)) circle times |Po-202; 11(-)> coupling, and it is depopulated through 286 keV E2 and 366 keV E3 transitions. In addition, we have observed a cascade of magnetic-dipole transitions which is suggested to be generated by the shears mechanism.

The very neutron-deficient isobars Pb-179 and Tl-179 have been produced using the fusion-evaporation reactions Pd-104(Kr-78,xpyn), where x <= 1 and y >= 2. The gas-filled separator RITU was employed to transport and separate the recoiling nuclei of interest from the scattered beam and unwanted products. The GREAT spectrometer was used to study the decay properties through alpha-alpha and alpha-gamma correlations, which has allowed the ground state of Pb-179 to be assigned as I-pi = 9/2(-). The decay of Pb-179 was measured to have an alpha-particle energy and half-life of E-alpha = 7348(5) keV and t(1/2) = 2.7(2) ms, respectively. A search for a nu i(13/2) state in Pb-179 was performed, but only a limit of excitation energy and half-life was obtained. In Tl-179 a t(1/2) = 114(-10)(+18) ns isomeric state, likely at an excitation energy of 904.5(9) keV, was identified and is tentatively assigned to be a 9/2(-) proton intruder state.

An experiment focused on the study of shape coexistence and new high-spin structures in Bi-195 has been performed. The nucleus is in a transitional region of the bismuth isotope chain. A large number of new states have been found, resulting in a significant extension of the previously known level scheme. Several new collective structures have been identified. A strongly coupled rotational band built upon the 13/2(+) isomeric state was extended up to I-pi = (49/2(+)) and an energy of 5706 keV. The I-pi = 31/2(+) member of the pi i(13/2) band was also found to feed a new long-lived isomeric state with an excitation energy of 2616 keV and a spin and parity of I-pi = 29/2(+). The half-life of the 29/2+ isomeric state was determined to be 1.49(1) mu s. It decays via the emission of 457-keV E2 and 236-keV E1 transitions, respectively. A low-energy 46-keV E2 transition has been identified to depopulate the (29/(2-)) isomeric state, with a measured half-life of T-1/2 = 614(5) ns. This transition allows the excitation energy of the isomeric state to be determined as 2381 keV. The feeding patterns of both 29/2(+) and (29/2(-)) isomeric states have also been described. This is the first time collective structures have also been observed up to high spins and excitation energies in the neutron-deficient Bi-195 nucleus. Evidence for the manifestation of shape coexistence in Bi-195 is also discussed.

A newly observed isomeric intruder 1/2(+) state [T-1/2 = 3.5( 6) ms] is identified in At-203 using a gas-filled recoil separator and fusion-evaporation reactions. The isomer is depopulated through a cascade of E3 and mixed M1/E2 transitions to the 9/2(-) ground state, and it is suggested to originate from the pi(s(1/2))(-1) configuration. In addition, the structures above the 1/2(+) state in At-203 and At-197 are studied using in-beam gamma-ray spectroscopy, recoil-decay tagging, and recoil-isomer decay tagging methods. The 1/2(+) state is fed from 3/2(+) and 5/2(+) states, and the origin of these states are discussed.