Calculation of the saturation properties of symmetrical nuclear matter with inclusion of & Delta -isobar
G. H. Bordbar
author
text
article
2020
per
One of the most interesting application of the many-body methods to the nuclear physics is the calculation of the properties of the nuclear matter, especially its binding energy. In this paper, we have studied the influence of Δ -isobar on the properties of the symmetrical nuclear matter using the lowest order constrained variational (LOCV) method with the V28 potential. It is shown that the inclusion of Δ- isobar substantially affect the saturation properties of the symmetrical nuclear matter. We have shown that, at low (high) densities, the saturation curve of nuclear matter is shifted downward (upward). This is due to the fact that the repulsive effect of the V28 potential increases by increasing density. It is seen that the equation of state of nuclear matter with the V28 potential is much harder than those with the A V14 potential.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
1
6
http://ijpr.iut.ac.ir/article_1467_515fa58b4ff99714a86d1d8cb6b55f6e.pdf
Directional anisotropy of magnetostriction and magnetic phase transition in Nd14 Dy2 Fe78 B6 solid solution
N.
T.
author
M. R.
A.
author
F.
P.
author
text
article
2020
per
In this research. The magnetic phase transition and anisotropic magnetoelastic effects of a polycrystalline sample of Nd14Dy2Fe78B6 were studied by susceptibility and magnetostriction measurements. The composition was prepared by casting method. SEM pictures and XRD analysis showed that it was composed of polycrystalline magnetic phases with the main phase of 2-14-1. Results of ac susceptibility measurements show that the sample undergoes a magnetic phase transition at about 130 K, which is due to a gradual spin reorientaion accompanied with crystal structure distortion. Magnetostriction measurements in three orthogonal directions of the main body of the sample were performed in the range of 77 K to 300 K and in the field up to 1.5 T. At temperatures below 125 K, the magnetostriction values in three orthogonal directions differ by a factor of two to three. This anisotropy in magnetostriction indicates preferential orientation of the crystalline grains in the volume of the sample. In addition, magnetostriction curves show minimum values near the phase transition temperature with different values in the different directions. Minimum values of magnetostriction can be explained by the critical behavior of the orbital magnetic moments of the Fe atoms at the phase transition temperature.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
7
12
http://ijpr.iut.ac.ir/article_1468_479426eca04e3b404a2f539ce5a9b53f.pdf
Fission fragment angular distributions in proton-induced fission of 209 Bi(p,t) and 197 Au(p,f)
S.
S.
author
N.
H.
author
M.
L.
author
text
article
2020
per
The fission fragment angular distributions have been measured for proton-induced fission of 209Bi and 197Au nuclei using surface barrier detectors at several energies between 25 MeV and 30 MeV. The experimental anisotropies are found to be in agreement with the predictions of the Standard Saddle-Point Statistical Model (SSPSM). The fission cross sections of 209Bi 197Au nuclei were also measured and compared with the previous works.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
13
26
http://ijpr.iut.ac.ir/article_1469_4c4a99cb01f80bb0b57be6b88fc34a6c.pdf
Calculation of point isotropic buildup factors of gamma rays for water and lead
A.
S. H.
author
M. H.
A.
author
text
article
2020
per
Exposure buildup factors for water and lead have been calculated by the Monte-Carlo method for an isotropic point source in an infinite homogeneous medium, using the latest cross secions available on the Internet. The types of interactions considered are ,photoelectric effect, incoherent (or bound-electron Compton). Scattering, coherent (or Rayleigh) scattering and pair production. Fluorescence radiations have also been taken into acount for lead. For each material, calculations were made at 10 gamma ray energies in the 40 keV to 10 MeV range and up to penetration depths of 10 mean free paths at each energy point. The results presented in this paper can be considered as modified gamma ray exposure buildup factors and be used in radiation shielding designs.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
27
38
http://ijpr.iut.ac.ir/article_1470_d0b984e049d4df7d9557482d94eb8b98.pdf
The Pr and Ca Substitution in GdBa2Cu3O7- & delta
H.
S. H.
author
M.
A.
author
text
article
2020
per
The granular Gd1-x-zPrxCazBa2Cu3O7-δ high-temperature cuprate samples with 0.0 ≤ x ≤ 0.3 and 0.0≤ x ≤ 0.35 are prepared by standard solid state reaction and characterized by XRD and SEM techniques. The BaCuO2 and impurity phases are less than 1% in the samples having high levels of pr and Ca concentrations. The electrical resistivity measurements show a nonlinear reduction in Tc(x,z=etc) versus x. Moreover, the Tc(z) curve with x=0 is nonlinear and aplateau appears at z≈ 0.05-0.015. For Pr-Ca-doped samples with a constant concentration of Pr, Tc increases with the increase of Ca up to an optimum value of Ca doping and then in decreases. Based on these observations, we suggest that hole filling and hole localization the main effects of Pr ion substiution. The magnetic measurements indicate that the value of Hc1 is in the order of 10 mT. The mangetoresistance measurements have been measured and analyzed. The superconducting transition region is broadened by the application of magnetic field. The experimental data near the onsen of superconductivity are fitted with the Ambegakor and Halperin (AH) phase-slip model. We observe that the AH parameter,γ (H), depends not only on the temperature and the magnetic field, but also on the Pr and Ca ions concentrations. It is observed that the critical current density increases with Ca substitution and decreases with Pr substitution in Gd-123 system. We suggest that the Pr ion substitution probably enhances the weak link, but the Ca ion acts as flux pinning center in the GdPrCa-123 system.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
39
50
http://ijpr.iut.ac.ir/article_1471_c97ceac126de5e9879b387ed67798ace.pdf
Nilpotent weights in conformal field theory
S. Rouhani
author
M. Saadat
author
Moghimi-Araghi
author
text
article
2020
per
Logarithmic conformal field theory can be obtained using nilpotent weights. Using such scale transformations various properties of the theory were derived. The derivation of four point function needs a knowledge of singular vectors which is derived by including nilpotent variables into the Kac determinant. This leads to inhomogeneous hypergeometric functions. Finally we consider the theory near a boundary and also introduce the concept of superfields where a multiplet of conformal fields are dealt with together. This leads to the OPE of superfields and a logarithmic partner for the energy momentum tensor.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
51
58
http://ijpr.iut.ac.ir/article_1472_dabaf56bdedfdc1ab3c50dd168c83c52.pdf
Electronic structure of Y-123 for ambient and high pressures
H.
K. H.
author
M. R.
M.
author
M.
A.
author
text
article
2020
per
The electronic properties of YBa2Cu3O7-δ have been investigated by the energy-pseudopotential method within the local density approximation (LDA) with and without including generalized gradient corrections (GGC). The band structure, density of states and charge density of YBa2Cu3O7- have been calculated. The results are compared with other approaches such as LAPW, LCAO and LMTO for this system. The overall shape of the band structure, density of states and charge density are in agreement with other works. However, in details, like other approaches, there are some differences. Considering our accuracy, the differences in results for LDA and GGC approaches are small. Also, the electronic and structural properties for this system have been investigated by applying pressure within LDA. We have calculated band structure, density of states, charge density, and length of bonds for high pressures, and the changes in hole concentration in this system with respect to pressure. Our results show the increase of hole in both CuO2 planes and Cu-O chains under high pressures. Although this result is in agreement with the pressure-induced charge transfer (PICT) model, it is in contrast with the definition of this model which believes that hole increases in the CuO2 planes come from the Cu-O chains. Bulk modules and equilibrium volume have been also calculated to be equal 184 Gpa and 174.89A03, respectively. The results of these calculations have been compared with the experimental and theoretical reports on this system.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
59
80
http://ijpr.iut.ac.ir/article_1473_fbda155071a099231c61e39810c504b1.pdf
Anomalous behavior in the light variations of RZ Cas
N. Riazi
author
M. R. Bagheri
author
A. Djanabzadeh
author
text
article
2020
per
UBV ligh curves together with color curves of the semi-detached eclipsing binary RZ Cas are presented. The light curves are analyzed and the spectroscopic elements and the Hipparcos information are used to compute the absolute parameters of the system. The light curve anomalies and occasional flat minima are discussed. Based on the existing evidence, a straightforward explanation for the primary minimum anomalies is presented.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
3
v.
1
no.
2020
81
81
http://ijpr.iut.ac.ir/article_1474_20fe06814f0ae863c9d586e4d0443cfd.pdf