Browsing by Author "Babacan, H"
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Item The effect of the pairing interaction on the energies of isobar analogue resonances in 112-124Sb and isospin admixture in 100-124Sn isotopesBabacan, T; Salamov, D; Kücükbursa, A; Babacan, H; Maras, I; Aygör, HA; Ünal, AIn the present study, the effect of the pairing interaction and the isovector correlation between nucleons on the properties of the isobar analogue resonances (IAR) in Sb112-124 isotopes and the isospin admixture in Sn100-124 isotopes is investigated within the framework of the proton-neutron quasi-particle random phase approximation (pnQRPA). The form of the interaction strength parameter is related to the shell-model potential by restoring the isotopic invariance of the nuclear part of the total Hamiltonian. In this respect, the isospin admixtures in the Sn100-124 isotopes are calculated, and the dependence of the differential cross section and the volume integral J(F) for the Sn(He-3,t)Sb reactions at E(He-3) = 200 MeV occurring by the excitation of IAR on mass number A is examined. Our results show that the calculated value for the isospin mixing in the Sn-100 isotope is in good agreement with Colo et al's estimates (4-5%), and the obtained values for the volume integral change within the error range of the value reported by Fujiwara et al (53 +/- 5 MeV fm(3)). Moreover, it is concluded that although the differential cross section of the isobar analogue resonance for the (He-3,t) reactions is not sensitive to pairing correlations between nucleons, a considerable effect on the isospin admixtures in N approximate to Z isotopes can be seen with the presence of these correlations.Item An investigation of the role of spectroscopic factors in the breakup reaction of 11BeCanbula, B; Bulur, R; Canbula, D; Babacan, HThe experimental elastic cross section data of the projectile Be-11 on target C-12 at 49.3 MeV/nucleon energy is analysed. The calculations for the elastic scattering are performed by the phenomenological optical model. The different optical potentials to include breakup effects into the calculations, which are neutron+C-12, neutron+ Be-10 and Be-10+C-12, are described with the aid of the global potentials for neutron interactions and fitted to experimental data for the core and target interaction. Also, the first analysis of the optical model for Be-10 on target C-12 at 39.1 MeV is done for building the interaction potential of the core and the target for Be-11. For investigating the effects of the spectroscopic factors, obtained factors from the direct capture process using the nuclear level density are compared with the previous cross section and spectroscopic factor results. Obtained results for the elastic cross section reproduce the experimental data very well and show the requirement of including spectroscopic properties such as, spectroscopic factors and density of the excited states, to explain this elastic cross section data.Item Renormalization of the γ-ray strength functions of light nucleiCanbula, B; Ersan, S; Babacan, Hgamma-ray strength function is the key input for the photonuclear reactions, which have a special astrophysical importance, and should be renormalized by using the nuclear level density for calculating the theoretical average radiative capture width, but performing such renormalization is challenging for light nuclei. With this motivation, recently introduced level density parameter formula including collective effects is used to calculate the average radiative capture width of light nuclei, and therefore to renormalize their gamma-ray strength functions. Obtained normalization factors are tested in (n, gamma) reactions for the necessity of renormalization for light nuclei.Item Nuclear level density as a tool for probing the inelastic scattering of 6HeCanbula, B; Babacan, HThe cross sections are calculated for the both elastic and inelastic scattering of He-6 from C-12 and He-4. A phenomenological optical potential is used to describe the elastic scattering. He-4 is taken as spherical and inelastic couplings to the first excited states of He-6 and C-12 are described with collective rotational model and coupled-channels method. Deformation lengths for He-6 and C-12 are determined from semi-classical nuclear level density model by using Laplace-like formula for the nuclear level density parameter. The comparison of the predicted and the measured cross sections are presented to test the applicability of nuclear level density model to the light exotic nuclei reactions. Good agreement is achieved between the predicted and measured cross sections.Item Probing 6He induced reactions with nuclear level densityCanbula, D; Canbula, B; Babacan, HIn this study, both elastic and inelastic cross sections of the light exotic nucleus He-6 on C-12 and He-4 at energies of 18 MeV, 30 MeV, 3.8 MeV, 4.2 MeV, 4.7 MeV, 5.1 MeV, 5.4 MeV, and 5.8 MeV, as well as the quasi-elastic cross section of He-6 on Be-9 at 16.2 MeV and 21.3 MeV, are calculated using the coupled-channel method. The deformation parameters of the first excited states of He-6, Be-9 and C-12 are obtained through the collective nuclear level density. The results align well with the available experimental data. It is demonstrated that the collective nuclear level density is essential to reduce the uncertainty between the deformation parameter and the optical model parameters. Furthermore, it is shown that the first excited state of both the projectile and the target must be considered in calculations He-6 + Be-9 scattering at increasing energies.Item A Laplace-like formula for the energy dependence of the nuclear level density parameterCanbula, B; Bulur, R; Canbula, D; Babacan, HCollective effects in the level density are not well understood, and including these effects as enhancement factors to the level density does not produce sufficiently consistent predictions of observables. Therefore, collective effects are investigated in the level density parameter instead of treating them as a final factor in the level density. A new Laplace-like formula is proposed for the energy dependence of the level density parameter, including collective effects. A significant improvement has been achieved in agreement between observed and predicted energy levels. This new model can also be used in both structure and reaction calculations of the nuclei far from stability, especially near the drip lines. (C) 2014 Elsevier B.V. All rights reserved.Item Effects of single-particle potentials on the level density parameterCanbula, B; Bulur, R; Canbula, D; Babacan, HThe new definition of the energy dependence for the level density parameter including collective effects depends strongly on the semi-classical approach. For this method, defining an accurate single-particle potential is of great importance. The effect of the single-particle potential terms, which are central, spin-orbit, harmonic oscillator, Woods-Saxon and Coulomb potential, both for spherical and deformed cases, on the level density parameter was investigated by examining the local success of the global parameterizations of eight different combinations of these terms. Among these combinations, the sum of the central, spin-orbit, harmonic oscillator and Coulomb potentials, gives the most accurate predictions compared with experimental data. The local selections of the global parameterizations show that the single-particle models, which are based on the Woods-Saxon potential as the main term, are more suitable candidates than the models based on harmonic oscillator potential to extrapolate away far from stability. Also it can be concluded that the contribution of the Coulomb interaction, both around the closed and open shells is not neglectable.Item Calculation of the level density parameter using semi-classical approachCanbula, B; Babacan, HThe level density parameters (level density parameter a and energy shift delta) for back-shifted Fermi gas model have been determined for 1136 nuclei for which complete level scheme is available. Level density parameter is calculated by using the semi-classical single particle level density, which can be obtained analytically through spherical harmonic oscillator potential. This method also enables us to analyze the Coulomb potential's effect on the level density parameter. The dependence of this parameter on energy has been also investigated. Another parameter, delta, is determined by fitting of the experimental level scheme and the average resonance spacings for 289 nuclei. Only level scheme is used for optimization procedure for remaining 847 nuclei. Level densities for some nuclei have been calculated by using these parameter values. Obtained results have been compared with the experimental level scheme and the resonance spacing data. (C) 2011 Elsevier B.V. All rights reserved.Item Analysis of elastic, quasielastic, and inelastic scattering of lithium isotopes on a 28Si targetCanbula, B; Canbula, D; Babacan, HThe elastic and inelastic cross sections of Li-6 on Si-28 at 240 MeV, and quasielastic cross section of Li-7 and Li-11 on Si-28 at 177.8 and 319 MeV, respectively, are analyzed with the coupled-channels method. The collective nuclear level density is used to determine the deformation parameter regarding to the first-excited state of Si-28. The results are in agreement with the experimental data and indicate the need of using a nuclear structure model such as nuclear level density to reduce the ambiguity between the optical model parameters and the deformation parameter. Additionally, the spin-orbit potential is found to have an important role in reproducing the data of the quasielastic scattering of Li-7 and Li-11 on a Si-28 target.Item An alternative approach to calculate the density of states in nonextensive statistical mechanicsBabacan, HA relation between the generalized partition function (Tsallis) and density of states is established by using the method of integral transform which enables reducing some integral equations into the algebraic equations. Inverse Mellin transformation of this equation gives the density of states. Similar relation is also hold the for standard partition function (Boltzmann-Gibbs) and the density of states. Using these relations, we recover the density of states for the classical ideal gas within both statistics. (C) 2010 Elsevier B.V. All rights reserved.Item Associative photoproduction of Roper resonance and ω meson -: art. no. 055208Babacan, H; Babacan, TAssociative photoproduction of omega meson and N-*(1440) on nucleons, gamma+N-->omega+N-*(1440), in the near threshold region is investigated in a framework employing effective Lagrangians. Besides pi exchange in the t channel, baryon exchanges, i.e., N and N-* exchanges, in the s and u channels are also taken into account in calculations of differential cross section and beam asymmetry. Important inputs of this model are the vector and tensor coupling constants of omegaNN(*)(1440) vertex, which are assumed to be equal to the values of these couplings for omegaNN vertex. Using our previous estimation of omegaNN coupling constants obtained from a fit to available experimental data on photoproduction of omega meson in the near threshold region, we produce the necessary numerical predictions for different observables in gamma+N-->omega+N-*(1440). Numerical results show that at low parallel totparallel to dominant contribution comes from t channel pi exchange while the effects of nucleon and N-*(1440) pole terms can be seen at large parallel totparallel to. Our predictions for the differential cross section and beam asymmetry for the processes gamma+N-->omega+N-*(1440), where N is proton and neutron, at E-gamma=2.5 GeV are presented with zero width approximation and also with the inclusion of width effects of N-*(1440).Item CALCULATION OF GENERALIZED LEVEL DENSITIES FOR NUCLEI IN MASS REGION 20 < A < 50Babacan, H; Kayacan, OIn this study, a relation between generalized level density and standard level density is derived. Using this relation and Bethe formula of Fermi gas model for standart level density we obtained a generalized nuclear level density formula for nucleus. Generalized level densities were calculated for some nuclei in mass region between 20 and 50 for different q values close to 1. Our results explain experimental data better than those of Gilbert-Cameron (GC) and Rohr, which are two of the leading compilations in evaluating nuclear level density.Item Effects of bisphosphonates on sutural bone formation and relapse: A histologic and immunohistochemical studyÖztürk, F; Babacan, H; Inan, S; Gümüs, CIntroduction: The aim of this experimental study was to evaluate the effects of systemically applied zoledronic acid on bone regeneration in response to expansion of the sagittal suture and relapse in rats. Methods: Thirty-six male Wistar rats were divided into 3 groups. In the first and second groups, saline solution was given subcutaneously after expansion, and the retention periods lasted 14 and 7 days, respectively. In the third group, 0.1 mg of zoledronic acid was diluted with saline solution and given subcutaneously after expansion; the retention period lasted for 7 days. Expansion and relapse amounts were measured by using computed tomography. After the retention period, 6 rats from each group were killed for histologic and immunohistochemical assessments. The other 6 rats from each group were used for observation of the relapse. Results: The histologic evaluation showed that, in groups 1 and 2, the numbers of osteoblasts were less than observed in group 3. When scores of staining intensity were compared, immunoreactivities were statistically significantly increased in group 3 compared with groups 2 and 1. Statistically significant differences were found when the relapse percentages were compared between the groups (P < 0.05). The smallest relapse occurred in group 3. Conclusions: Zoledronic acid has positive effects on bone formation in the sagittal suture in response to expansion and decreases the relapse ratio after expansion in rats. (Am J Orthod Dentofacial Orthop 2011; 140: e31-e41)