International Journal of Modern Physics E

The radiative capture reaction ${}^{13}\mathrm{\text{C}}{(p,\gamma )}^{14}\mathrm{\text{N}}$ is analyzed using a hybrid model approach where the non-resonant component has been constructed employing the potential model with a folded M3Y potential. The one-level Breit–Wigner formula has been used to estimate the cross-sections of the resonant decays of dominant ($1^{-}$) state of ${}^{14}$N at 8.06MeV. The contribution of the broad resonance at 8.77MeV ($0^{-}$) has been dealt with differently. While Breit–Wigner formula has been used where the excitation function data exist, the $R$-matrix prediction for the cross-section of decay to a bound state of ${}^{14}$N from the broad resonance has been used where excitation function data are not available. The single particle spectroscopic factors for ground and six excited states of ${}^{14}$N have been obtained from the fits. The resulting astrophysical $S$-factor at zero relative energy is $6.84\pm 0.77$keV b. The value is in good agreement with the previously reported $R$-matrix result and also consistent within error bars with the published values.

We implement the Heisenberg principle into the Constrained Molecular Dynamics model with a similar approach to the Pauli principle using the one-body occupation probability ${\bar{f}}_i$. Results of the modified and the original model with comparisons to data are given. The binding energies and the radii of light nuclei obtained with the modified model are more consistent with the experimental data than the original one. The collision term and the density distribution are tested through a comparison to p+${}^{12}$C elastic scattering data. Some simulations for fragmentation and superheavy nuclei production are also discussed.

Magnetic dipole moments of the ground- and excited-states below 600keV in ${}^{183,185}$W, ${}^{185,187}$Re and ${}^{187,189}$Os nuclei have been systematically studied in the framework of a microscopic Quasiparticle Phonon Nuclear Model (QPNM) including an axially symmetric Wood–Saxon potential as a mean field and the residual spin–spin interaction. The obtained results of the magnetic moment, intrinsic $g_K$ factor and the effective spin gyromagnetic factor have been compared with the available experimental data and also with the calculations based on different approaches. It has been demonstrated that the QPNM reproduces reasonably well the recent experimental value of the ground-state magnetic moment and satisfactorily describes the measured magnetic moment of low-lying states below 600keV in these nuclei.

We have examined the binding energy, root-mean-square radii and two neutrons separation energies for the recently accepted super-heavy element $Z=118$ established as Og using the axially deformed relativistic mean field (RMF) model with NL3 force parameter set. The calculation is extended to various isotopes of $Z=118$ element, starting from $A=290$ till $A=310$. The most stable isotope is found to be at $N\sim 174(A=292,Z=118)$. Also, the $\alpha$-decay energy $Q_{\alpha }$ and hence the half-lives $T_{\alpha }$ is carried out by taking three different empirical formulae for the $\alpha$-decay chains of $Z=118$ supporting the possible shell closure at daughter nuclei $N=170$ and/ or 184 and at parent nucleus of $N=192$ with $Z=118$.

The half-lives of the $\alpha$ decay for even–even nuclei having $Z=62–118$ (164 nuclei) have been calculated by using the Wentzel–Kramers–Brillouin (WKB) method together Bohr–Sommerfeld (BS) quantization condition for cosh potential in two-different forms with and without the isospin effects for six different parameter sets. By comparing the obtained results with the experimental values, the rms deviations have been computed. It is obtained that when the cosh potential is used in 2 different type forms, the rms values are also changed and the better one for obtaining the half-lives is cosh-2 form. Even if the isospin-dependent potential does not have so much effect on rms values in this sort of WKB with BS calculations with cosh potential forms, considering the isospin effect together the isospin-dependent nuclear diffuseness parameter have a strong influence on the rms values. New hindrance factor formula based on liquid drop model was used in order to show the influence of hindrance factor on the $\alpha$ decay half-lives. It is pointed out that this new function of the hindrance factor does not depend on the magic numbers, it contains fewer free parameters and using of this improves the calculations positively. New estimates by using present model have also been made for even–even nuclei having with $Z=118–120$ which do not have the measured $\alpha$ decay half-lives yet and they have been compared the results of the ImSahu model. The present results would provide useful information and knowledge for the explanation of half-lives of $\alpha$ decay of nuclei and future possible experimental studies.

The $\alpha$-decay (AD) half-life (HL) of ${}^{\text{186–218}}$Po $(Z=84)$ isotopes is studied systematically within the modified Coulomb and proximity potential model (MCPPM). The computed HLs are compared with the existing theoretical formulae including Royer, AKRE, Ren B and MRen B. This study considers the role of neutron shell closure $N=126$ on the AD HLs. The comparison with the experimental data indicates the acceptability of the results.

The evolution of contact binary star systems in mass asymmetry (transfer) coordinate is considered. The orbital period changes are explained by an evolution in mass asymmetry towards the symmetry (symmetrization of binary system). It is predicted that decreasing and increasing orbital periods are related, respectively, with the nonoverlapping and overlapping stage of the binary star during its symmetrization. A huge amount of energy $\mathrm{\Delta }U\approx 10^{41}$J is converted from the potential energy into internal energy of the stars during the symmetrization. As shown, the merger of stars in the binary systems, including KIC 9832227, is energetically an unfavorable process. The sensitivity of the calculated results to the values of total mass and orbital angular momentum is analyzed.

$Q$-value and half-life of elements in alpha decay chain of ${}^{294}$117, ${}^{293}$117, ${}^{291}$116 and ${}^{290}$116 were calculated using the Nuclear potential generated by double folding procedure and using the WKB method treating the alpha decay as a tunneling problem. The nuclear potential was parameterized using Woods–Saxon potential. Using this approach, the $Q$-value and half-life of next heaviest element in the alpha decay chain of element ${}^{290}$116 is predicted. It is proposed to use this to predict the $Q$-value and half-life of other higher elements in different alpha decay chains.

The nucleus–nucleus reaction cross-sections of ${}^{22-36}\mathrm{\text{Na}}+{}^{12}$C and ${}^{19-27}\mathrm{\text{F}}+{}^{12}$C at 240MeV/u are calculated using the optical limit of the Glauber model. The deformation and radii of a deformed Fermi density are calculated from the relativistic mean field (RMF). The results are compared with the recent experimental data. It is found that the Fermi density whose quadrupole deformation parameters and radii are derived from RMF, using TMA effective interaction in the RMF Lagrangian, provide a satisfactory explanation of the experimental data of Na isotopes, except for ${}^{30,31}$Na, which are expected to be strongly deformed. For F isotopes, the deformed Fermi density adjusted to the radii derived from RMF, using TMA interaction, presents a lower reaction cross-section. The Lagrangian parameters set NL3* gives a good description of the data which is better than that predicted by TMA. On the other hand, the two forces cannot describe the reaction cross-section of ${}^{27}$F since it is expected to have a deformed halo structure. The radius deduced from the data is found to be of the order 3.5fm.

We investigate the contribution of partonic interactions between incident nucleons and produced mesons to the dilepton continuum in heavy-ion reactions. A schematic model is employed in order to calculate the resulting Drell–Yan yield as a function of collision energy and for different scenarios concerning the formation of hadrons. The secondary Drell–Yan process is found to be significant for invariant masses $m\approx 1.5$GeV in central $A+A$ collisions around $\sqrt{s_{\mathrm{\text{NN}}}}\approx 15-20$GeV, but less so at much lower or much higher energies. Secondary Drell–Yan dileptons should be observable in experiments due to their distinct rapidity dependence as a characteristic deviation from the well-known (primary) Drell–Yan contribution due to $N+N$ interactions. The predicted strong dependence of the secondary Drell–Yan contribution on the nuclear collision energy can be used to experimentally probe the effective hadronic formation time of secondaries.