D. N. Basu

α decay half-lives of new superheavy elements

The lifetimes of \ensuremath{\alpha} decays of the recently produced isotopes of elements 112, 114, 116, and

Predictions of alpha decay half lives of heavy and superheavy elements

{}^{294}118

MODIFIED BETHE–WEIZSÄCKER MASS FORMULA WITH ISOTONIC SHIFT AND NEW DRIPLINES

and of some decay products are calculated theoretically within the WKB approximation by use of microscopic \ensuremath{\alpha}-nucleus interaction potentials. We obtain these nuclear potentials by folding the densities of the \ensuremath{\alpha} and the daughter nuclei with the M3Y effective interaction, supplemented by a zero-range pseudopotential for exchange along with the density dependence. Spherical charge distributions are used for calculating the Coulomb interaction potentials. These calculations provide reasonable estimates for the observed \ensuremath{\alpha} decay lifetimes and thus provide reliable predictions for other superheavies.

α decay chains from element 113

Abstract Theoretical estimates for the lifetimes of several isotopes of heavy elements with Z = 102 – 120 are presented by calculating the quantum mechanical tunneling probability in a WKB framework and using microscopic nucleus–nucleus potential obtained by folding the densities of interacting nuclei with the DDM3Y effective nuclear interaction. The α -decay half lives calculated in this formalism using the experimental Q -values are in good agreement over a wide range of experimental data. Half lives are also calculated using Q -values extracted from two mass formulae. The Viola–Seaborg–Sobiczewski (VSS) estimates of α -decay half lives with the same Q -values are presented for comparison. The half life calculations are found to be quite sensitive to the choice of Q -values. Comparison with the experimental data delineates the inadequacies of older mass predictions in the domain of heavy and superheavy elements as compared to the newer one by Muntian–Hofmann–Patyk–Sobiczewski, and highlights necessity of a more accurate mass formula which can predict Q -values with even higher precision.

Spontaneous heavy cluster emission rates using microscopic potentials

Nuclear masses are calculated using the modified Bethe–Weizsacker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic–macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe–Weizsacker mass formula with isotonic shifts.

Cluster radioactivity in very heavy nuclei: a new perspective

Theoretical estimates of {alpha}-decay half-lives of several nuclei in the decay from element 113 are presented. Calculations in a WKB framework using DDM3Y interaction and experimental Q-values are in good agreement with the experimental data. Half-life calculations are found to be quite sensitive to the Q-values and angular momentum transfers. Calculated decay lifetime decreases, owing to more penetrability as well as thinner barrier, as Q-value increases. Deviations to this predominant behavior observed in some recent experimental data may be attributed to nonzero spin-parities in some cases.

Lambda hyperonic effect on the normal drip lines

The nuclear cluster radioactivities have been studied theoretically in the framework of a microscopic superasymmetric fission model (MSAFM). The nuclear interaction potentials required for binary cold fission processes are calculated by folding in the density distribution functions of the two fragments with a realistic effective interaction. The microscopic nuclear potential thus obtained has been used to calculate the action integral within the WKB approximation. The calculated half lives of the present MSAFM calculations are found to be in good agreement over a wide range of observed experimental data.

Isospin dependent properties of asymmetric nuclear matter

Abstract Exotic cluster decay of very heavy nuclei is studied using the microscopic nuclear potentials obtained by folding density dependent M3Y effective interaction with the densities of the cluster and the daughter nuclei. The microscopic nuclear potential, Coulomb interaction and the centrifugal barrier arising out of spin-parity conservation are used to obtain the potential between the cluster and the daughter nuclei. Half life values are calculated in the WKB framework and the preformation factors are extracted. The latter values are seen to have only a very weak dependence on the mass of the emitted cluster.

Nuclear half-lives for α-radioactivity of elements with 100 ⩽ Z ⩽ 130

A generalized mass formula is used to calculate the neutron and proton drip lines of normal and lambda hypernuclei treating non-strange and strange nuclei on the same footing. Calculations suggest the existence of several bound hypernuclei whose normal cores are unbound. Addition of Λ or ΛΛ hyperon(s) to a normal nucleus is found to cause non-uniform shifts of the neutron and proton drip lines from their conventional limits making existance of a few exotic hypernuclei beyond the normal drip lines possible.

Proton radioactivity with a Yukawa effective interaction

AbstractThe density dependence of nuclear symmetry energy is determined from a system-atic study of the isospin dependent bulk properties of asymmetric nuclear matterusing the isoscalar and the isovector components of density dependent M3Y in-teraction. The incompressibility K ∞ for the symmetric nuclear matter, the isospindependent part K asy of the isobaric incompressibility and the slope L are all inexcellent agreement with the constraints recently extracted from measured isotopicdependence of the giant monopole resonances in even-A Sn isotopes, from the neu-tron skin thickness of nuclei and from analyses of experimental data on isospindiffusion and isotopic scaling in intermediate energy heavy-ion collisions. This workprovides a fundamental basis for the understanding of nuclear matter under extremeconditions, and validates the important empirical constraints obtained from recentexperimental data. PACS numbers : 21.65.-f, 21.30.Fe, 21.10.Dr, 26.60.Kp Key words: EoS; Symmetry energy; Incompressibility; Isobaric incompressibility.