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Öğe Alpha decay investigations of Bi isotopes(Indian Assoc Cultivation Science, 2023) Koyuncu, F.; Soylu, A.; Alavi, S. A.; Dehghani, V; Kocak, G.The alpha decay half-lives of Bismuth isotopes have been investigated systematically by using Wentzel- Kramers-Brillioun (WKB) method and the Bohr-Sommerfeld quantization condition. Three forms of the potentials; Woods-Saxon (WS), Woods-Saxon Squared (WS2) and hybrid potentials have been used to describe the nuclear interaction between the alpha and daughter nuclei. Present results have been compared with the experimental data and results of previous calculations. We have obtained better agreement with the experimental data by using WS2 potential than other potentials.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 Calculations on the proton decay with modified preformation probability(World Scientific Publ Co Pte Ltd, 2022) Soylu, A.; Koyuncu, F.; Alavi, S. A.; Dehghani, V.In this paper, the investigations have been conducted on the half-lives of proton radioactivity of 32 nuclei. The main goal of the paper is to improve the formation probability (S-p) that proposed by Chen et al. [Eur. Phys. J. A 57 (2021) 1]. The obtained results in mentioned paper have been reproduced with uncertainties for all parameters by fitting the experimental data of proton emitters. To carry out the further investigations, we have proposed a new S-p which has a different type of shape from linear. The replacement of the linear form with an exponential, one of the formation probabilities, has affected the rms result positively. The new form of S-p, which has been presented in this study, depends on the mass number of daughter nucleus like the previous one but in exponential form. The obtained findings here may be important for studies while making new predictions.Öğe Cluster decay half-lives using asymmetry dependent densities(Iop Publishing Ltd, 2022) Dehghani, V; Alavi, S. A.; Razavi, R.; Soylu, A.; Koyuncu, F.By adopting different neutron and proton density distributions, cluster decay half-lives were investigated using double-folding potentials with constant and nuclear asymmetry dependent sets of nuclear density parameters. Two adopted asymmetry dependent sets of parameters were fitted based on microscopic calculations, and they were calculated based on the neutron skin/halo-type nuclei assumption and by employing experimental rms charge radii. A bulk agreement between theory and experiment was obtained for all sets of parameters using a calculated cluster preformation probability. Few differences were observed between the skin and halo-type assumptions. However, the notable role of the asymmetry parameter was observed in the relatively large differences between the skin and skin-type with zero thickness.Öğe ?-decay half-lives of uranium isotopes using a two-potential approach(Amer Physical Soc, 2024) Alavi, S. A.; Dehghani, V.; Soylu, A.; Koyuncu, F.Using three methods, the two-potential approach (TPA), the direct method, and the distorted-wave method, the decay widths of uranium isotopes were calculated. Wider ranges of application of the TPA were checked and independence of the decay width to the separation point, from the prebarrier position to the postbarrier position, was observed. The equivalence of the direct and the distorted-wave methods for spherical nuclei was discussed Simplified versions of the TPA and the direct method were used and satisfactory results for the TPA version and the same results for two forms of the direct method were obtained. By presenting different experimental half-lives with remarkable uncertainties, especially for lighter isotopes, the calculated preformation probabilities using the TPA bound wave function and the TPA decay width were compared and reasonable agreement was observed for favored transitions.Öğe Heavy ion fusion reaction cross section: Analysis of the temperature dependence of the repulsive nuclear potential(Amer Physical Soc, 2020) Ghorbani, F.; Alavi, S. A.; Dehghani, V; Soylu, A.; Koyuncu, F.Using the Wong formula, fusion cross sections of O-18+ Cu-63, O-18+ Pt-194, O-16+ Pb-208, and C-12+ Pr-141 reactions are calculated with double-folding potentials (M3Y) and inclusion of the corrected temperature-dependent repulsive nuclear potential (M3Y + rep). Two different values of repulsive diffuseness are selected in calculations and effect of nuclear temperature on the repulsive nuclear potential, the effective potential, and three parameters of the Wong formula are investigated. Our results show that the inclusion of temperature-dependent repulsive nuclear potential increases the effective potential in interior regions, noticeably. However, in the near-barrier region, little enhancement of the effective potential causes small variations in the barrier height, position, and frequency. Better agreement between theory and experiment is observed by including the repulsive nuclear potential.Öğe Proton radioactivity half-lives with nuclear asymmetry factor(Iop Publishing Ltd, 2021) Soylu, A.; Koyuncu, F.; Gangopadhyay, G.; Dehghani, V.; Alavi, S. A.The dependence of proton emission half-lives on the nuclear asymmetry parameter is investigated using the WKB method and two types of empirical formula. Using the single-folding formalism with asymmetry-dependent nuclear radius and surface diffuseness of nuclear matter, the nuclear potential and consequently the half-life are functions of the asymmetry factor. Despite small values of asymmetry in neutron-deficient proton emitters, noticeable changes in the half-lives are observed. The addition of an asymmetry parameter term to the two forms of empirical formulas leads to a reduction in the rms error for ground state and isomeric transitions. A noticeable reduction of about 43% is obtained for isomeric transitions in the second form of the empirical formula. Considering ground state transitions in two categories, odd-even and odd-odd emitters, and adopting deformation and asymmetry-dependent empirical formulas, the rms decreases remarkably. The lowest values of rms errors, viz. 0.1492, 0.2312, and 0.1999, are obtained for the aforementioned empirical formulas for ground state transitions of odd-even and odd-odd emitters and for all isomeric transitions, respectively.Öğe PROTON-RADIOACTIVITY HALF-LIFE FORMULAS WITH ISOSPIN AND SHELL EFFECTS(Jagiellonian Univ Press, 2020) Soylu, A.; Koyuncu, F.; Alavi, S. A.; Dehghani, VWe have investigated the influence of isospin and shell effects on the proton decay half-lives of nuclei. In order to take into account these effects, new parameters related with isospin and shell effects have been added to the empirical formulas proposed in Phys. Rev. C 79, 054330 (2009) and Chin. Phys. C 42, 014104 (2018). The parameters of these new empirical formulas including isospin and shell effects have been fitted by 44 experimental available data comprising 29 ground states and 15 isomeric transitions of proton decay half-lives. The r.m.s. deviation between theory and experiment is decreased by inclusion of these modifications. The models have been applied to proton decaying nuclei whose experimental values are not yet known and then to actinide nuclei as well. Results consistent with the ones in the literature have been obtained. The role of the isospin and shell effects on the proton decay half-lives has been demonstrated.Öğe Search for ?-decay chains for superheavy nuclei with Z=125-127(Elsevier, 2021) Aliyeva, G.; Soylu, A.; Koyuncu, F.We have studied the alpha-decay (AD) and spontaneous fission (SF) properties of the isotopes of Z=125, 126 and 127 superheavy nuclei. AD calculations have been performed over all the possible isotopes of Z=125-127 nuclei within the framework of Wentzel-Kramers-Brillouin (WKB) and Bohr-Sommerfeld quantization condition. To broaden the perspective of the calculations, we have also utilized from the ana-lytic formula of Royer in the calculations of AD. In this way we believe that by using various approaches might be useful for the clarity of the predictions. Also, the SF half-lives have been computed by using formulae of Soylu and KPS. Decay modes for the isotopes are determined by using the results of different models. The decay modes obtained for Z=125 and Z=126 have been compared with the results of other studies, and alpha-decay chains have been presented for Z=127. Findings would provide opportunities for the future experimental researches. (c) 2021 Elsevier B.V. All rights reserved.Öğe The alpha-decay chains and decay mode predictions of the nuclei Z=118, 119 and 120(World Scientific Publ Co Pte Ltd, 2020) Koyuncu, F.; Soylu, A.The alpha decay (AD) chains of the nuclei having Z = 118, 119 and 120 have been investigated in terms of different theoretical models. Decay mode results that are presented in this study have been probed over the possible isotopes of the aforementioned nuclei. In the decay mode predictions, the formula of Bao et al. and the formula proposed by Soylu have been used to calculate the spontaneous fission (SF) half-lives. The AD half-lives have been computed by using the Denisov and Khuedenko, Royer, Horoi, the universal decay law (UDL), the Viola-Seaborg-Sobiczewski (VSS), the universal curve (UNIV) formulas and Wentzel-Kramers-Brillouin (WKB) approximation with BohrSommerfeld quantization condition for the nuclei that have the measured experimental half-lives. Therefore, the rms values of the results of the related expressions and WKB method have been determined, in this way, AD half-life calculations of the Z = 118, 119 and 120 nuclei have been performed. According to the obtained results, SF half-life values for Bao et al. and Soylu are quite different from one approach to another, the predictions on decay modes of the Z = 118, 119 and 120 nuclei show differences. The decay modes produced by using different models used in this study would be important for the predictions of the future experimental investigations.Öğe The predictions on the heavier cluster decays of superheavy nuclei(Springer, 2019) Soylu, A.; Koyuncu, F.We have calculated the half-lives of the a and heavy-cluster decays of superheavy nuclei in the framework of the Wentzel-Kramers-Brillouin (WKB) method. Good agreement with the present experimental data with the WKB method and Universal Decay Law (UDL) has been obtained for the a-decay half-lives of superheavy nuclei having proton numbers with 107 <= Z <= 118. We have utilized the cluster preformation factor form proposed by Santhosh and Nithya [9] with new parameters sets produced by fitting of the results with the UDL formula in order to obtain the cluster decay half-lives. Reasonable results have been obtained by using the cluster preformation factor together with the WKB formalism for the cluster decays. Furthermore, ratio calculations have been performed to find out the candidates of possible cluster emitters. The predictions for cluster emitters are in agreement with estimates with the CPPM model by Santhosh and Nithya [9] and new additional estimates with the WKB and UDL are made. The present results and predictions would be important for both the theoretical and experimental studies in this field.
