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[en] We have investigated the halo formation in the neutron rich Ca isotopes within the framework of recently proposed relativistic mean-field plus BCS (RMF+BCS) approach wherein the single particle continuum corresponding to the RMF is replaced by a set of discrete positive energy states for the calculation of pairing energy. For the neutron rich Ca isotopes in the vicinity of neutron drip-line, it is found that further addition of neutrons causes a rapid increase in the neutron rms radius with a very small increase in the binding energy, indicating thereby the occurrence of halos. This is essentially caused by the gradual filing in of the loosely bound 3s1/2 state. Interesting phenomena of accommodating several additional neutrons with almost negligible increase in binding energy is shown to be due to the pairing correlations (Authors)
[en] In this mass region a systematic investigation of the ground as well as high spin structures of 164-170Dy isotopes following the approach with pairing+quadrupole+hexadecapole model interaction Hamiltonian was carried out
[en] We have made theoretical investigations on the structure of high spin states of 160-170Dy isotopes to supplement the current experimental progress being made on the production and spectroscopy of neutron-rich Dy nuclei with mass number A=166 and 168. The calculations have been carried out within the framework of cranked Hartree-Fock-Bogolyubov (CHFB) theory employing a pairing + quadrupole + hexadecapole model interaction. Our results for the g factors show a remarkable variation as a function of angular momentum while moving from 164Dy to neutron-rich isotopes 166-170Dy. This is explained in terms of relative rate of change in proton and neutron single-particle contributions to the total aligned angular momentum as the system acquires higher spins. Amongst single-particle orbitals, the πh11/2 and νi13/2 states and their respective positions from the proton and neutron Fermi levels are found to play the most crucial role. A comparison with the available experimental data shows that our calculated spin dependence of g-factor values for yrast states in the stable isotopes 160,162,164Dy are consistent with the recent measurements of Brandolini et al
[en] In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number A = 166 and 168, we have made theoretical investigations on the structure of high spin states of 164-170Dy isotopes in the cranked Hartree-Fock-Bogoliubov (CHFB) theory employing a pairing + quadrupole + hexadecapole model interaction. With the increase of neutron number the rotation alignment of the proton orbitals dominates the structure at high spins, which is clearly reflected in the spin dependence of the rotational g-factors. A particularly striking feature is the difference in the spin-dependent properties of 166Dy as compared to that of 164Dy. (author)
[en] In the present investigations we have employed relativistic mean-field plus BCS (RMF + BCS) approach to study the variation of root mean square radii and the density profiles for the entire chain of even even N = 28 isotones upto drip-lines. Root mean square radii for the nuclei of the N = 28 isotonic chain obtained from our deformed RMF + BCS calculations and spherical RMF + BCS calculations with TMA force parameters have been displayed along with the available experimental data for the purpose of comparison. It is observed that with increasing number of protons the rms radius for the proton distribution rp increases gradually to have maximum value for the heaviest bound nucleus 3058Zn28 for N = 28 isotonic chain. A comparison shows that the deformed RMF results for the nuclei with Z = 12, 14 and 16 are not similar to those obtained from the spherical RMF calculations as the nuclei with Z = 12, 14 and 16 are appreciably deformed
[en] A systematic study of the ground-state properties of the entire chains of even–even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82, and 126 has been carried out using relativistic mean-field plus Bardeen–Cooper–Schrieffer approach. Our present investigation includes deformation, binding energy, two-proton separation energy, single-particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using nonrelativistic approach (Skyrme–Hartree–Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip-lines, the (Z, N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.
[en] In the present investigations we have employed relativistic mean-field plus BCS (RMF + BCS) approach to carry out a systematic study for the ground state properties of even-even C Isotopes. One of the prime reason of this study has been to look into the role of low lying states in neutron rich reason near neutron drip line. It is found that irrespective of whether any resonant state exists or not, the occupancy of weakly bound neutron single particle states having low orbital angular momentum, (l = 0 or 1), with a well spread wave function due to the absence or very small strength of centrifugal barrier, helps to cause the occurrence of nuclei with widely extended neutron density. Such nuclei are found to have characteristically very small two-neutron separation energy and large neutron rms radius akin to that observed in weakly bound systems.
[en] The study of high-spin states in Kr isotopes near A = 80 region has attracted a considerable interest in recent years. A variety of shapes, shape coexistence as well as backbending phenomenon have been studied in the many of Kr isotopes. In the case of 80Kr, the high spin structure has been studied by Doring et al. rather extensively and has provided considerable insight into the structure of f-p-g shell nuclei and the competition between single-particle and collective degrees of freedom. Backbending phenomenon is reported in 80Kr at ω = 0.5 MeV
[en] The traditional neutron magic nuclei with N = 8, 20, 28, 50, 82 and 126, and those with neutron sub-magic number N = 40 are investigated within the relativistic mean-field plus BCS (RMF+BCS) approach. The results indicate appearance of new proton magic numbers as well as the disappearance of conventional magic numbers for nuclei with extreme isospin values. The calculated energies and densities do not indicate any tendency for the proton halo formations in any of the proton rich isotones due to Coulomb interaction and different single particle spectra. However, the potential barrier provided by the Coulomb interaction and that due to the centrifugal force may cause a long delay in the actual decay of proton rich nucleus resulting in the extended drip line. (authors)