Low-Energy Nuclear Excitations along the α-Decay Chains of Superheavy ^{292}Lv and ^{294}Og.

We present the first triaxial beyond-mean-field study of the excitation spectra of even-even superheavy nuclei. As representative examples, we have chosen the members of the α-decay chains of ^{292}Lv and ^{294}Og, the heaviest even-even nuclei which have been synthesized so far using ^{48}Ca-induced fusion-evaporation reactions. In our calculations, the effective finite-range density-dependent Gogny force is used and the angular-momentum and particle-number symmetries are restored.

Spectroscopy along Flerovium Decay Chains: Discovery of ^{280}Ds and an Excited State in ^{282}Cn.

A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively.

Predominance of Triaxial Shapes in Transitional Super-Heavy Nuclei: Ground-State Deformation and Shape Coexistence along the Flerovium (Z=114) Chain of Isotopes.

We present the first triaxial beyond-mean-field study of even-even super-heavy nuclei. Calculations for the even Flerovium isotopes towards the supposed N=184 neutron shell closure were performed using the effective finite-range density-dependent Gogny force. They include the restoration of the particle-number and angular-momentum symmetries and the mixing of different shapes using the generator coordinate method.

Collective and Single-Particle Motion in Beyond Mean Field Approaches.

We present a novel nuclear energy density functional method to calculate spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole deformations and rotational frequencies are considered simultaneously as the degrees of freedom within a symmetry conserving configuration mixing framework. The present method allows the study of nuclear states with collective and single-particle character.

Shape and pairing fluctuation effects on neutrinoless double beta decay nuclear matrix elements.

Nuclear matrix elements (NME) for the most promising candidates to detect neutrinoless double beta decay have been computed with energy density functional methods including deformation and pairing fluctuations explicitly on the same footing. The method preserves particle number and angular momentum symmetries and can be applied to any decay without additional fine tunings. The finite range density dependent Gogny force is used in the calculations.

Shape coexistence near neutron number N=20: first identification of the E0 decay from the deformed first excited Jpi=0+ state in 30Mg.

The 1789 keV state in 30Mg was identified as the first excited 0+ state via its electric monopole (E0) transition to the ground state. The measured small value of rho2(E0,0(2)+-->0(1)+)=(26.2+/-7.

New beyond-mean-field theories: examination of the potential shell closures at N=32 or 34.

A beyond-mean-field theory of new generation has been developed and applied for the first time to discuss the controversial N=32 and/or N=34 shell closures and the puzzling behavior of the transition probabilities from the ground to the first 2(+) state in the titanium isotopes. In the numerical applications, the finite range density dependent Gogny interaction has been used. As compared with the experimental data for several calcium, titanium, and chromium isotopes, we obtain a good agreement for the excitation energies and a reasonable one for the transition probabilities.

Unveiling the origin of shape coexistence in lead isotopes.

Shape coexistence in the nuclei (182-192)Pb is analyzed with the Hartree-Fock-Bogoliubov approach and the Gogny force. Good agreement with the experimental energies is found for the coexisting spherical, oblate, and prolate states. Contrary to the established interpretation, it is found that the low-lying prolate and oblate 0+ states are predominantly characterized by neutron correlations whereas the protons behave, in general, rather as spectators than playing an active role.

Fission barriers at high angular momentum and the ground state rotational band of the nucleus 254No.

We study the superheavy nucleus 254No in the framework of the Hartree-Fock-Bogoliubov approximation with the finite-range density-dependent Gogny force, at zero and high angular momentum. The properties of the ground state rotational band and the fission barriers are discussed as a function of angular momentum. We found a two-humped barrier up to spin values of (30-40)Planck's over 2pi and a one-humped barrier for higher spins.

Behavior of shell effects with the excitation energy in atomic nuclei.

We study the behavior of shell effects, like pairing correlations and shape deformations, with the excitation energy in atomic nuclei. The analysis is carried out with the finite temperature Hartree-Fock-Bogoliubov method and a finite range density dependent force. For the first time, properties associated with the octupole and hexadecupole deformation and with the superdeformation as a function of the excitation energy are studied.

Phase transitions above the Yrast line in 154Dy.

Spectra of the E2 quasicontinuum gamma rays feeding different spin regions of the 154Dy yrast line have been extracted. These are compared with corresponding theoretical spectra obtained by numerical simulations based on temperature-dependent Hartree-Fock theory, with thermal shape fluctuations. In this manner, different regions of the spin-energy plane can be examined.