Skyrme–Hartree–Fock–Bogoliubov Calculations of Even and Odd Neutron-Rich Mg Isotopes

Using the Skyrme functional with SIII, SKM*, SLy4, and UNE0 sets of parameters and the Hartree–Fock–Bogoliubov mean-field method; the ground-state properties of even-even and even-odd neutron-rich Mg isotopes have been investigated. The results of calculations of the binding energy per nucleon (B/A), the one- and two-neutron separation energies (Sn and S2n), proton and neutron rms radii, neutron pairing gap, and quadrupole deformation parameter (B2) have been compared with the available experimental data, the results of Hartree–Fock–Bogoliubov calculations based on the D1S Gogny force, and predictions of some nuclear models such as the Finite Range Droplet Model (FRDM) and Relativistic Mean-Field (RMF) model. Our results show good agreements in comparison with the experimental data and the results of the mentioned models.

Nuclear Structure Evolution Reflected from Local Relations

The structure evolution of nuclei which are in connection with symmetry breaking is one of the important problems not only for nuclear structures, but also for astrophysics and the spectroscopy of exotic nuclei. Many physical quantities can provide useful information of a shell structure, such as nuclear masses and nuclear charge radii. This paper introduces three kinds of local relations, i.e., the NpNn scheme respectively for the quadrupole deformation parameter and the excitation energy of the first 2+, 4+, 6+ states, the (αN′n+N′p) relation for nuclear charge radii and α decay energies, and the so-called “nonpairing” relation for binding energies and nuclear charge radii. All these relations reflect the evolution of nuclear structures, involving shells, subshells, shape coexistence, phase transition and the Wigner effect. Some results from different models can be verified with each other.

Structural and decay properties of nuclei appearing in the α-decay chains of 296,298,300,302,304120 within the relativistic mean field formalism

An extensive study of [Formula: see text]-decay half-lives for various decay chains of isotopes of [Formula: see text] is performed within the axially deformed relativistic mean-field (RMF) formalism by employing the NL3, NL3[Formula: see text], and DD-ME2 parameter set. The structural properties of the nuclei appearing in the decay chains are explored. The binding energy, quadrupole deformation parameter, root-mean-square charge radius, and pairing energy are calculated for the even–even isotopes of [Formula: see text], which are produced in five different [Formula: see text]-decay chains, namely, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. A superdeformed prolate ground state is observed for the heavier nuclei, and gradually the deformation decreases towards the lighter nuclei in the considered decay chains. The RMF results are compared with various theoretical predictions and experimental data. The [Formula: see text]-decay energies are calculated for each decay chain. To determine the relative numerical dependency of the half-life for a specific [Formula: see text]-decay energy, the decay half-lives are calculated using four different formulas, namely, Viola–Seaborg, Alex–Brown, Parkhomenko–Sobiczewski and Royer for the above said five [Formula: see text]-decay chain. We notice a firm dependency of the half-life on the [Formula: see text]-decay formula in terms of [Formula: see text]-values for all decay chains. Further, this study also strengthens the prediction for the island of stability in terms of magic number at the superheavy valley in the laboratories.

Scattering of α-particles by 11B nuclei at an energy of 40MeV and role of the exchange mechanism with transfer of 7Li

The elastic and inelastic scatterings of [Formula: see text]-particles were investigated at an energy of 40[Formula: see text]MeV with excitation of low-lying states of the [Formula: see text]B nucleus [0.0 (3/2[Formula: see text]), 4.445 (5/2[Formula: see text]), 6.74 (7/2[Formula: see text]), 2.125 (1/2[Formula: see text]) and 5.02[Formula: see text]MeV (3/2[Formula: see text])]. The analysis of the experimental angular distributions was carried out via the coupled channels method within the framework of the collective model. The value of the quadrupole deformation parameter [Formula: see text] was extracted. Calculations indicate a preference for a negative sign for deformation. It is shown that the exchange mechanism with the transfer of the heavy 7Li cluster does not play an important role in the scattering of [Formula: see text]-particles on [Formula: see text]B nuclei at an energy of 40[Formula: see text]MeV.

Decay properties and reaction dynamics of zirconium isotopes in the relativistic mean-field model

In the framework of relativistic mean-field theory, the ground state properties like binding energy, charge radius and quadrupole deformation parameter for various isotopes of zirconium from the valley of stability to drip-line region have been studied. The results are compared with the experimental data and we found reasonable agreement. The calculations are carried out for [Formula: see text]-decay energy and [Formula: see text]-decay half-life up to the drip-line. Total reaction and elastic differential cross-sections are also studied for few zirconium isotopes as projectiles with [Formula: see text] as target, using different parameter sets namely NL3*, DD-ME2 and DD-PC1 in conjunction with Glauber model.

Fast-timing measurements in neutron-rich odd-mass zirconium isotopes using LaBr3:Ce detectors coupled with Gammasphere

A fast-timing experiment was performed at the Argonne National Laboratory to measure the lifetimes of the lowest lying states of nuclei belonging to the deformed regions around mass number A≃110 and A≃150. These regions were populated via spontaneous fission of 252Cf and the gamma radiation following the decay of excited states in the fission fragments was measured using 51 Gammasphere detectors coupled with 25 LaBr3:Ce detectors. A brief description of the acquisition system and some preliminary results from the fast-timing analysis of the fission fragment 100Zr are presented. The lifetime value of τ = 840(65) ps was found for the 2+ state in 100Zr consistent within one standard deviation of the adopted value with 791 +26 -35ps. This is associated with a quadrupole deformation parameter of 0.36(2) which is within one standard deviation of the literature value of 0.3556+82 -57.

GROUND STATE PROPERTIES AND BUBBLE STRUCTURE OF SYNTHESIZED SUPERHEAVY NUCLEI

We calculate the ground state properties of recently synthesized superheavy elements (SHEs) from Z = 105–118 along with the predicted proton magic Z = 120. The relativistic and nonrelativistic mean field formalisms are used to evaluate the binding energy (BE), charge radius, quadrupole deformation parameter and the density distribution of nucleons. We analyzed the stability of the nuclei based on BE and neutron to proton ratio. We also studied the bubble structure which reveals the special features of the superheavy nuclei.

PROPERTIES OF Z = 120 NUCLEI AND THE α-DECAY CHAINS OF THE 292, 304120 ISOTOPES USING RELATIVISTIC AND NONRELATIVISTIC FORMALISMS

The ground state and first intrinsic excited state of superheavy nuclei with Z = 120 and N = 160–204 are investigated using both nonrelativistic Skyrme–Hartree–Fock (SHF) and the axially deformed relativistic mean field (RMF) formalisms. We employ a simple BCS pairing approach for calculating the energy contribution from pairing interaction. The results for isotopic chain of binding energy (BE), quadrupole deformation parameter, two neutron separation energies and some other observables are compared with the finite range droplet model (FRDM) and some recent macroscopic–microscopic calculations. We predict superdeformed ground state solutions for almost all the isotopes. Considering the possibility of magic neutron number, two different modes of α-decay chains 292120 and 304120 are also studied within these frameworks. The Qα-values and the half-life [Formula: see text] for these two different modes of decay chains are compared with FRDM and recent macroscopic–microscopic calculations. The calculation is extended for the α-decay chains of 292120 and 304120 from their excited state configuration to respective configuration, which predicts long half-life [Formula: see text] (in seconds).

THE α-DECAY CHAINS OF THE 287, 288115 ISOTOPES USING RELATIVISTIC MEAN FIELD THEORY

We study the binding energy, root-mean-square radius and quadrupole deformation parameter for the synthesized superheavy element Z = 115, within the formalism of relativistic mean field theory. The calculation is dones for various isotopes of Z = 115 element, starting from A = 272 to A = 292. A systematic comparison between the binding energies and experimental data is made.The calculated binding energies are in good agreement with experimental result. The results show the prolate deformation for the ground state of these nuclei. The most stable isotope is found to be 282115 nucleus (N = 167) in the isotopic chain. We have also studied Qα and Tα for the α-decay chains of 287, 288115.

CLUSTERING CORRELATIONS AND TRIAXIALITY IN THE sd-SHELL REGION

Effects of cluster correlations on triaxiality have been studied using the antisymmetrized molecular dynamics. Low-lying states in 28 Si and 40 Ca are obtained by the the generator coordinate method (GCM), and the GCM basis are calculated by energy variations with constraints on quadrupole deformation parameter β and inter-cluster distance. The GCM obtain prolate superdeformed (SD) states in 28 Si and triaxial normal-deformed (ND) states in 40 Ca , which contain prolate α-24 Mg and triaxial α-36 Ar cluster structure components, respectively. Different shapes of prolate 24 Mg and oblate 36 Ar clusters cause difference of triaxiality of total systems. Cluster correlations which have oblate cluster enhance triaxiality in excited states.