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Öğe alpha-alpha folding cluster model for alpha-radioactivity(SPRINGER, 2015) Soylu, A.; Bayrak, O.The -decay half-lives are calculated for heavy and superheavy nuclei for and from the ground state to ground state transitions within the framework of the Wentzel-Kramers-Brillouin (WKB) method and the Bohr-Sommerfeld quantization. In the calculations, the - single folding cluster potential obtained with the folded integral of the - potential with the -cluster density distributions is used in order to model the nuclear interaction between the -particle and core nucleus. While the results show very good agreement with the experimental ones in the heavy-nuclei region, especially for even-even nuclei, smaller values than the experimental ones are obtained for superheavy nuclei. As both the density of the core and the interaction term in the folding integral include the -clustering effects and, in this way, all cluster effects are taken into account in the model, the results of calculations are more physical and reasonable than the calculations done in the other models. The present method could be applied to light nuclei with different types of nuclear densities.Öğe An approximate solution of Dirac-Hulthen problem with pseudospin and spin symmetry for any kappa state(AMER INST PHYSICS, 2007) Soylu, A.; Bayrak, O.; Boztosun, I.For any spin-orbit quantum number kappa, the analytical solutions of the Dirac equation are presented for the Hulthen potential by applying an approximation to spin-orbit coupling potential for the case of spin symmetry, Delta(r)=C=const, and pseudospin symmetry Sigma(r)=C=const. The bound state energy eigenvalues and the corresponding spinors are obtained in the closed forms.Öğe Binary cluster model calculations for 20Ne and 44Ti nuclei(World Scientific Publ Co Pte Ltd, 2017) Koyuncu, F.; Soylu, A.; Bayrak, O.The elastic scattering data of alpha+O-16 and alpha+Ca-40 systems at E-lab = 32.2-146 MeV and E-lab = 24.1-49.5 MeV energies have been analyzed with double-folding (DF) potential in optical model formalism in order to investigate the cluster structures of Ne-20 and Ti-44 nuclei. The deduced DF potentials between alpha and O-16 as well as alpha and Ca-40 have been used for obtaining the excitation energies and alpha-decay widths of Ne-20 and Ti-44 in Gamow code, but the reasonable results could not be obtained. Thus, the real parts of DF potentials which are in the best agreement with experimental data have been fitted with the squared-Woods-Saxon (WS2) potential parameters to calculate the alpha-decay widths of Ne-20 and Ti-44 with Wentzel-Kramers-Brillouin (WKB) approach. The nuclear potential sets obtained in WKB calculations are also used for Gamow code calculations. We take into account the deformation and orientation of Ca-40 nucleus to examine their influence on both the excitation energies and decay widths of Ti-44. Besides, by using the binary cluster model the rotational band energies and electromagnetic transition probabilities (BE2)s according to angles are also reproduced for both nuclei. The obtained results showed that the binary cluster model is very useful to understand the observables of Ne-20 and Ti-44 nuclei. Although only spherical calculations are made for Ne-20 (alpha + O-16), the deformation in Ca-40 would be important for the understanding of Ti-44 (alpha + Ca-40) cluster structure. The mechanism presented here would also be applied to understand the cluster structures in heavy nuclei.Öğe Effect of external fields on the energies of hydrogenic donor with the anharmonic confinement potential(ELSEVIER SCIENCE BV, 2015) Aciksoz, E.; Bayrak, O.; Soylu, A.The impurity binding energy in the GaAs-Ga1-x AlxAs system is studied with an anharmonic type confinement potential by taking into account the influence of the external electric and magnetic fields within the framework of the effective mass approximation and asymptotic iteration method (AIM). The influence of the external electromagnetic fields and anharmonicity on a donor binding energy is examined systematically. It is shown that the donor binding energy is highly dependent on the external electric and magnetic fields and the confinement potential shapes. Both the electric and magnetic fields are increased, the binding energies increase for each of them. However, the behaviors of increase in the weak and strong fields' regimes have different character a bit. Furthermore, when the more anharmonicity is considered, the binding energy of donor slightly increases as well. (C) 2014 Elsevier By. All rights reserved.Öğe Effect of nuclear deformation on alpha-decay half-lives(AMER PHYSICAL SOC, 2012) Coban, A.; Bayrak, O.; Soylu, A.; Boztosun, I.We systematically investigate the influence of nuclear deformations on the alpha-decay half-lives of the deformed medium, heavy, and superheavy nuclei for 106 <= A <= 273 and 52 <= Z <= 110 from the ground state to ground state alpha transitions within the framework of the Wentzel-Kramers-Brillouin (WKB) method by considering the Bohr-Sommerfeld quantization condition. The deformed Wood-Saxon form in a phenomenological way and the deformed Coulomb potential in a special form have been used in order to take into account all deformation effects in the calculations and the preformation of the parent nuclei have also been regarded. Calculations have been conducted for the spherical nuclei in order to present clearly the effects of the deformations on the half-lives. We point out that all considerations have improved the results and very good agreement has been obtained with experimental data.Öğe Effect of the Velocity-Dependent Potentials on the Bound State Energy Eigenvalues(IOP PUBLISHING LTD, 2011) Bayrak, O.; Soylu, A.; Boztosun, I.We investigate the effect of isotropic velocity-dependent potentials on the bound state energy eigenvalues for the first time for any quantum states of the Coulomb and harmonic oscillator potentials within the framework of the asymptotic iteration method. When the velocity-dependent term is selected as a constant parameter rho(0), we present that the energy eigenvalues can be obtained analytically for both Coulomb and harmonic oscillator potentials. However, when the velocity-dependent term is considered as a harmonic oscillator type rho(0)r(2), taking the velocity-dependent term as a perturbation, we present how to obtain the energy eigenvalues of the Coulomb and harmonic oscillator potentials for any.. and l quantum states by using perturbation expansion and numerical calculations in the asymptotic iteration method procedure.Öğe Exact solutions of Klein-Gordon equation with scalar and vector Rosen-Morse-type potentials(IOP PUBLISHING LTD, 2008) Soylu, A.; Bayrak, O.; Boztosun, I.We obtain an exact analytical solution of the Klein-Gordon equation for the equal vector and scalar Rosen-Morse and Eckart potentials as well as the parity-time ( PT) symmetric version of the these potentials by using the asymptotic iteration method. Although these PT symmetric potentials are non-Hermitian, the corresponding eigenvalues are real as a result of the PT symmetry.Öğe Kappa State Solutions of Dirac-Hulthen and Dirac-Eckart Problems with Pseudospin and Spin Symmetry(AMER INST PHYSICS, 2008) Soylu, A.; Bayrak, O.; Boztosun, I.; Boztosun, I; Balantekin, ABIn this study, the analytical solutions of the Dirac equation have been presented for the Hulthen and Eckart potentials by applying an approximation to centrifugal-like term in the case of spin symmetry, Delta(r)=C=constant, and pseudospin symmetry, Sigma(r)=C=constant, for any spin-orbit quantum number x. The energy eigenvalues and corresponding spinor wave functions are obtained in the closed-forms.Öğe kappa state solutions of the Dirac equation for the Eckart potential with pseudospin and spin symmetry(IOP PUBLISHING LTD, 2008) Soylu, A.; Bayrak, O.; Boztosun, I.For any spin-orbit coupling term kappa, the analytical solutions of the Dirac equation for the Eckart potential are presented by using the asymptotic iteration method within the framework of the spin and pseudospin symmetry concept. The energy eigenvalues are obtained in the closed form by applying an approximation to the spin-orbit coupling potential.Öğe Role of the cluster deformations in explaining the exotic decay half-lives(SPRINGER, 2012) Soylu, A.; Sert, Y.; Bayrak, O.; Boztosun, I.We investigate the influence of nuclear deformations of the cluster and daughter nuclei on the exotic cluster decay half-lives of 221 <= A <= 242 for the favored cluster decay of the radioactive nuclei by using the semiclassical WKB method and the Bohr-Sommerfeld quantization condition. The results have also been presented for the spherical nuclei case in order to show clearly the effects of the deformations on the exotic decay half-lives. The half-lives become close to the experimental data when both the deformation of daughter and cluster nuclei are taken into account in the calculations. Furthermore, considering cluster deformations together with the orientation angles of daughter and cluster also provides positive contributions to the results.Öğe The energy eigenvalues of the two dimensional hydrogen atom in a magnetic field(WORLD SCIENTIFIC PUBL CO PTE LTD, 2006) Soylut, A.; Bayrak, O.; Boztosun, I.In this paper, the energy eigenvalues of the two dimensional hydrogen atom are presented for the arbitrary Larmor frequencies by using the asymptotic iteration method. We first show the energy eigenvalues for the case with no magnetic field analytically, and then we obtain the energy eigenvalues for the strong and weak magnetic field cases within an iterative approach for n = 2 - 10 and m = 0 - 1 states for several different arbitrary Larmor frequencies. The effect of the magnetic field on the energy eigenvalues is determined precisely. The results are in excellent agreement with the findings of the other methods and our method works for the cases where the others fail.Öğe The influence of nuclear deformations on the exotic cluster decay half-lives(IOP PUBLISHING LTD, 2015) Soylu, A.; Bayrak, O.; Evlice, S.We systematically study the investigation of the influence of nuclear deformations of the cluster and daughter nuclei on the exotic cluster decay half-lives of heavy nuclei by the WKB method and the Bohr-Sommerfeld quantization condition. Even if the deformations of both cluster and daughter in the half-live values of cluster decays improve the results, considering the deformation of clusters is more efficient than the deformation of daughter for the heavy cluster decay half-live calculations. Moreover, taking into account of angle orientations of daughter and cluster provides a positive contributions to the results as well. The results would be useful for experimental researches in half-lives of exotic decays of some heavy nuclei and radium isotopes.Öğe The relativistic treatment of spin-0 particles under the rotating Morse oscillator(AMER INST PHYSICS, 2010) Bayrak, O.; Soylu, A.; Boztosun, I.We present the energy eigenvalues and corresponding normalized eigenfunctions of the relativistic spin-0 particles by solving the Klein-Gordon equation. Analytical forms for the energy eigenvalues and eigenfunctions have been derived by using Pekeris approximation to the centrifugal term within the framework of the asymptotic iteration method for the equal vector and scalar rotating Morse oscillator. The eigenvalue equation results in a transcendental form, in which the numerical values are presented in atomic units for arbitrary n and quantum states. (c) 2010 American Institute of Physics. [doi:10.1063/1.3503413]
