International Journal of Science and Research (IJSR) ISSN: 2319-7064 ResearchGate Impact Factor (2018): 0.28 | SJIF (2018): 7.426 Volume 8 Issue 10, October 2019 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Calculation of Astrophysical S-factor for the 60 Ni(p,) 61 Cu Reaction Below Coulomb Barrier Animesh Kumer Chakraborty Department of Physics, Chittagong University of Engineering and Technology, Chittagong-4349, Bangladesh Abstract: Astrophysical S-factor was calculated for the reaction 60 Ni(p,) 61 Cu, on the basis of experimental cross-section data, as a function of the incident proton energy ranges from 1.49 MeV to 3.96 MeV. Since the literature values of this reaction is rather scarcein low-energy region, the astrophysical S-factor was calculated which describes the possibility of the reaction to occur. The Coulomb- barrier potential, Sommerfeld parameter and the Gamow factor were also calculated in the centre-of-mass(C.M) system for the estimation of the probability of penetrating the Coulomb barrier through tunneling effect which leads to an insight of the mechanism of low-energy light-charged particle capture reactions those are very important for astrophysical aspects. Keywords: Astrophysical S-factor, (p,)-reaction, excitation function, reaction threshold, Coulomb barrier, Gamow factor, Sommerfeld parameter 1. Introduction Nuclear reactions cross sections such as the radiative capture (p,γ), (α,γ), (n,γ)etc are of crucial interest in astrophysics, since they play an important role in basic processes such as steller burning,evolution of stars, nucleosynthesis [1]. It is well known that the experimental cross sections at energies far below the Coulomb barrier (i.e., steller energy region) are very scarce due to the fact that the probability of the tunneling effect decreases, hence cross sections drop for energies. As a result, precise determination of cross-sections in the threshold energy region becomes difficult (because the Coulomb barrier exponentially suppresses low-energy cross sections). Although it is true that measurements of nuclear reaction cross-sections for charged-particle induced reactions can be extended toward lower energies with improved experimental techniques, but in practice one can hardly reach the stellar energy region. This has lead to the implementation of indirect methods allowing the experimental difficulties inherent to the direct measurements of capture cross-section to be circumvented. Generally, cross sections at low energy can be obtained by extrapolation from the values measured at higher energies, preferably with the help of some theoretical considerations. However, cross-sections for charged particle induced reactions that depends on energymakes this extrapolation difficult. Thus, for extrapolationat very low energies below the Coulomb barrier, instead of using the cross section, it is more convenient to use the much less energy dependent quantity, the astrophysical S-factor, S(E). In fact, the astrophysical S-factor of the reaction changes slowly with incident-particle energy (i.e., weakly depends on energy), thus this factor removes the coulomb dependence and only accounts the nuclear effects, hence evolved as more convenient in separating the energy dependence of Coulomb barrier penetration from the cross sections [2].For astrophysical applications, one needs to know the value of S- factor for many reactions at low energies. In respect of the formation of medium mass elements via nucleosynthesis in stellar process, the 60 Ni(p,) 61 Cu reaction has a significant importance. A number of authors have proposed different models and techniques in the last few decades for the calculations of astrophysical parameters for reactions those are important for understanding the overall mechanisms of stellar processes [1-10]. In fact, depending on temperature, density and other parameters, stellar burning may involve many reactions of different nuclei, from light to heavy, and from stable to neutron- and proton-rich ones. The aim of this work is to calculate the astrophysical s-factor along with other related parameters for the reaction 60 Ni(p,) 61 Cu using the experimental cross-sections measured recently at the Tandem Accelerator Facilities Division, INST, AERE, Dhaka, Bangladesh [11] and to compare the results with theoretical model calculations using TALYS 1.8 codes. 2. Theory In some cases, the height of the Coulomb barrier becomes orders of magnitude higher than the energy of the interacting charged particles during the non-explosive nucleosynthesis. So, the quantum mechanical tunneling is the only way for the reactions to occur. The probability of penetrating the Coulomb barrier via tunneling effect is Where c R  is the so-called classical turning point and n R  is the nuclear radius. At low energies where c E E ฀ (equivalently where c n R R   ฀ ), this probability can be approximated with Where  is the Sommerfeld parameter, And the Gamow factor Paper ID: ART20201886 10.21275/ART20201886 1737