SearcharxivSearch

arXiv subjects

R. Gharaei

Publications and source records attributed to R. Gharaei.

6 recordsLinked to original sources

Role of universal function of the nuclear proximity potential: A systematic study on the alpha-decay of heavy/super-heavy nuclei and {\alpha}-induced reactions

The idea of the universal function is fundamental advantage of proximity potential model. We present a systematic study of the role of universal function of the proximity potential model on alpha decay process for 250 ground state to ground state transitions using WKB approximation. In order to realize this goal, five universal functions proposed in the proximity models gp 77, Guo 2013, Ngo 80, Zhang 2013 and Prox. 2010 have been incorporated into the formalism of Prox. 77. The obtained results show that the radial behavior of universal function affects the penetration probability of the {\alpha} particle. The theoretical {\alpha} decay half lives are calculated and compared with the corresponding experimental data. It is shown that the Prox. 77 with Guo 2013 universal function provides the best fit to the available data. The role of the different universal functions in the {\alpha} decay half lives of super heavy nuclei (SHN) with Z from 104 to 118 are also studied. It is shown that the experimental half lives in the super heavy mass region are described well using the Prox. 77 with Zhang 2013 universal function. In this paper, the validity of the original and modified forms of the proximity 77 potential is also examined for complete fusion reactions between {\alpha} particle and 10 different target nuclei. Our results show that the measured {\alpha} induced fusion reaction cross sections can be well reproduced using the Prox. 77 with Zhang 2013 universal function for the reactions involving light and medium nuclei. Whereas, the Prox. 77 with Guo 2013 universal function model demonstrates a reliable agreement with the experimental data at sub-barrier energies for heavier systems.

nucl-th

The nuclear surface diffuseness effects on the alpha decay of heavy and super heavy nuclei

We select 300 different parent nuclei in the range Z from 64 to 106. The proximity potentials Zhang 2013 and Guo 2013 are employed to calculate the nuclear potential. The influence of the nuclear surface diffuseness is applied in the calculations of interaction potential between the emitted alpha particle and daughter nucleus through the reduced radius parameter. The systematic analysis of the radial behavior of interaction potential with and without the surface diffuseness effect reveals that these effects play decisive role in the calculation of nucleus-nucleus potential at the touching radius of the two interacting nuclei. We indicate that its influence decreases outside the touching configuration. In addition, our results reveal that the barrier penetration probability of the alpha particle through the barrier decreases by imposing the mentioned physical effects. It is worth noting that the calculated alpha-decay half-lives using the Zhang 2013 and Guo 2013 proximity potentials accompanied by the surface effects agree very well with the available experimental data. The theoretical halflives are calculated for 50 super-heavy nuclei using the modified forms of the Zhang 2013 and Guo 2013 models. The comparison with available experimental data and also with different empirical formulas demonstrates that the Guo 2013 model is suitable to deal with the alpha decay half-lives of SHN. Then the predictions of alpha decay half-lives for 65 SHN with Z from 120 to 126 are made by using Guo 2013 model with the surface effects. We found that there is a good agreement between our predicted half-lives and those obtained from semi-empirical formulas such as Royer and UDL.

nucl-th

Impacts of EMC effects on the D meson modification factor in equilibrating QGP

In this article we employ the nuclear EMC effect to extract the parton distribution functions (PDFs) inside the Lead (Pb) and Gold (Au) nuclei. Extracted PDFs are utilized to obtain the transverse momentum dependent (TMD) ones, using the computing codes like Pythia 8 or MCFM-10. Through this procedure TMDPDFs for charm and bottom quarks in Au at $\sqrt{s_{NN}}=200\;GeV$, Pb at $\sqrt{s_{NN}}=2.76\;TeV$ and $\sqrt{s_{NN}}=5.02\;TeV$ are calculated. To evaluate the validity of results and investigate the influence of nuclear EMC effect, the numerated TMDs are used as input to estimate heavy quark modification factor $R_{AA}$ at transverse plane $P_T$. This observable is calculated through numerical solution of the Fokker-Planck equation. For this purpose we need to extract the drag and diffusion coefficients, using the hard thermal loop correction. It is done in the frame work of the relativistic hydrodynamics up to the third order approximation of gradient expansion. The results are compared with same solutions when the input PFDs are considered inside the unbounded protons where the nuclear effect is not included. The comparison indicates a significant improvement of computed $R_{AA}$ with available experimental data when the EMC effect is considered.

hep-ph

Systematic study of the isotopic dependence of fusion dynamics for neutron- and proton-rich nuclei using a proximity formalism

The behaviors of barrier characteristics and fusion cross sections are analyzed by changing neutron over wide range of colliding systems. For this purpose, we have extended our previous study (Eur. Phys. J. A \textbf{48}, 21 (2012), it is devoted to the colliding systems with neutron-rich nuclei) to 125 isotopic systems with condition of $0.5\leq N/Z \leq 1.6$ for their compound nuclei. The AW 95, Bass 80, Denisov DP and Prox. 2010 potentials are used to calculate the nuclear part of interacting potential. The obtained results show that the trend of barrier heights $V_B$ and positions $R_B$ as well as nuclear $V_N$ and Coulomb $V_C$ potentials (at $R=R_B$) as a function of ($N/Z-1$) quantity are non-linear (second-order) whereas the fusion cross sections follow a linear-dependence.

nucl-th

The study of the nucleus-nucleus interaction potential for $^{16}$O+$^{27}$Al and $^{16}$O+$^{28}$Si fusion reactions

Using the Monte Carlo simulation method accompanied by the modifying effects of the density distributions overlapping, we have examined the nuclear matter incompressibility effects for asymmetric systems with light nuclei, namely $^{16}$O+$^{27}$Al and $^{16}$O+$^{28}$Si fusion reactions. The obtained results show that the nuclear equation of state has considerable influence on the calculation of fusion probabilities for these asymmetric systems.

nucl-th

The systematic study of the influence of neutron excess on the fusion cross sections using different proximity-type potentials

Using different types of proximity potentials, we have examined the trend of variations of barrier characteristics (barrier height and its position) as well as fusion cross sections for 50 isotopic systems including various collisions of C, O, Mg, Si, S, Ca, Ar, Ti and Ni nuclei with $1\leq N/Z < 1.6$ condition for compound systems. The results of our studies reveal that the relationships between increase of barrier positions and decrease of barrier heights are both linear with increase of $N/Z$ ratio. Moreover, fusion cross sections also enhance linearly with increase of this ratio.

nucl-th