Structure Of Superheavy Elements Research Articles

Covariant density functional theory: Reexamining the structure of superheavy nuclei

A systematic investigation of even-even superheavy elements in the region of proton numbers $100 \leq Z \leq 130$ and in the region of neutron numbers from the proton-drip line up to neutron number $N=196$ is presented. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range and deformation effects are taken into account. This allows us to assess the spread of theoretical predictions within the present covariant models for the binding energies, deformation parameters, shell structures and $\alpha$-decay half-lives. Contrary to the previous studies in covariant density functional theory, it was found that the impact of $N=172$ spherical shell gap on the structure of superheavy elements is very limited. Similar to non-relativistic functionals some covariant functionals predict the important role played by the spherical $N=184$ gap. For these functionals (NL3*, DD-ME2 and PC-PK1), there is a band of spherical nuclei along and near the $Z=120$ and $N=184$ lines. However, for other functionals (DD-PC1 and DD-ME$\delta$) oblate shapes dominate at and in the vicinity of these lines. Available experimental data are in general described with comparable accuracy and do not allow to discriminate these predictions.

Project of the experimental setup dedicated for gamma and electron spectroscopy of heavy nuclei at FLNR JINR

Important information on the structure of super heavy elements (SHE) can come from the study of lighter deformed transfermium (Z∼100–106) elements. The cross-section for the formation of these nuclei is many orders of magnitude higher than for Z⩾110 so that detailed spectroscopy becomes possible. The advantage of Dubna is the unique possibility to use radioactive actinide targets, which yield higher production cross-sections for heavy elements. The use of actinide targets also makes Dubna a complementary site for heavy element spectroscopy because, until the availability of intense radioactive beams, it is the only way to produce less neutron deficient heavy isotopes. The opportunity to have high intensity (⩾1pμA) accelerated beams with A⩽40 together with the use of exotic targets provide the possibility to study many aspects of heavy ion induced reactions exploiting new generation of high efficiency, high resolution experimental setups. The scientific fields of the application of the new setup could be concentrated on the study of asymmetric combinations leading to excited heavy compound nuclei.

Feature Article: Developments in Spectroscopic Studies of Deformed Superheavy Nuclei

The search for new elements and the study of their structure and decay properties has been in the forefront of nuclear physics for decades, especially since detailed theoretical predictions of the existence of superheavy elements (SHE) appeared in the mid 1960s. The heaviest elements offer a unique possibility to study the effective nuclear interaction because of the delicate interplay of attractive nuclear and disruptive Coulomb forces. Nuclides with proton number higher than 104 (rutherfordium, Rf) or so survive against fission only because of quantum effects that build up a fission barrier. The understanding of the structure of SHE is essential for the development of mean field theories that are used to predict nuclear properties far from stability.

New Development in the Theory of Superheavy Nuclei

We investigate the predictions of modern self-consistent microscopic approaches for the shell structure of superheavy elements. Special emphasis is being laid on the ability of the models to describe spin-orbit splittings in known nuclei, which is a crucial ingredient of the models when it comes to extrapolations of shell structure.