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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 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.
