Critical properties of the classical Heisenberg and XY models : A mean field renormalization group study
A. Sadeghi
author
F. Shahbazi
author
text
article
2019
per
Using both mean field renormalization group (MFRG) and Surface-Bulk MFRG (SBMFRG), we study the critical behavior of the classical Heisenberg and XY models on a simple cubic lattice. Critical temperatures as well as critical exponents, characteristic the universality classes of these two models were calculated, analytically for1, 2, 3 and 4 spin clusters. The results are in good agreement with higher accurate methods such as Monte Carlo and High- temperature series.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
1
6
http://ijpr.iut.ac.ir/article_560_daa80c8d46a9fedeb23ceb56a94b4b0b.pdf
Transition from asymmetric to symmetric fission in 45-69 MeV proton induced fission of 238U
H. Noshad
author
text
article
2019
per
Thin targets of 238U were bombarded with 45, 55, 65 and 69 MeV protons at the Cyclotron and Radioisotope Center (CYRIC) of Tohoku University in Japan. Gamma rays emitted from the fission products were recorded and analyzed by using gamma spectroscopy. Then, the cross sections for the formation of fission products, fragment mass distributions, and total fission cross sections were measured. Special care was taken to make this measurement precisely. The experimental results show that for 238U(p, f) reaction at Ep < /sub> > 65 MeV, the asymmetry component in the mass distribution is eliminated, and the symmetric fission remains the dominant fission mode.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
7
13
http://ijpr.iut.ac.ir/article_561_c20ea84d42841f09acf4177fbd9a4fa8.pdf
The classically conformal invariant scalar theory with a non-positive potential
Vahid Kamali
author
Farhang Loran
author
text
article
2019
per
We review the conformal symmetry group and investigate the isomorphism between the conformal group and O( D,2 ) . We study the classically conformal invariant scalar theory in D -dimensions with a non-positive potential . We solve the equations of motion by assigning O(D-1, 2)symmetry to the classical solutions with broken translational symmetry in all directions. Then we consider a six dimensional theory and obtain a set of classical solutions, which are invariant under translation in four out of six directions. We make use of them to construct an effective four dimensional scalar theory induced by the fundamental six dimensional theory. Finally we elaborate the most general solutions of the ø4 massless model in four dimensions.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
15
22
http://ijpr.iut.ac.ir/article_562_787fe6d85114dc2726b70e37696e37ce.pdf
Delocalization of elastic waves in disorder harmonic chain with random distribution of force constants
M. Rahimi
author
F. Shahbazi
author
text
article
2019
per
Using inverse participation ratio and level statistics analysis, we investigate the localization of the natural modes of a disordered harmonic chain in which the force constants are distributed randomly without correlation as well as with long-range power-law (c ( l ) ~ l-y ) correlation. We find that for a specific value of correlation exponent the localized modes turn to be extended.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
23
29
http://ijpr.iut.ac.ir/article_563_04d04349c0161d18c8f2723b51dfa8b3.pdf
Determination of optimum proton pulse duration for triggering fast ignition in inertial confinement fusion
A. Ghasemizad
author
M. J. Tabatabai
author
text
article
2019
per
Two relatively simple analytic Models for investigation of fast ignition dynamics are developed, that are the subsonic and the supersonic models. On the basis of the subsonic model, which a pre-compressed fuel of density is heated by a subsonic thermal wave, the beam energy and the intensity required for ignition is closely related to proton range. Whereas, on the basis of supersonic model, for ranges shorter than 0.25 gr/cm2 , the mentioned energy remains constant and the intensity decreases. For ranges larger than this value, not only energy but also the beam intensity will increase with the proton range. Considering that proton pulse duration depend on proton range implicitly, these results allow for the determination of an optimum proton pulse duration value, that we have obtained this value equal to 2.14×103 p < sub>o-1 ps.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
31
41
http://ijpr.iut.ac.ir/article_564_f0fcbf5f9600490833b19065ef710614.pdf
Analyze of Mn K-edge resonance X-ray scattering in Nd0.5Sr0.5MnO3
A. Mohammadi Tabar
author
M. E. Ghazi
author
H. Arabshahi
author
text
article
2019
per
Studies of phenomena such as charge, orbital and spin ordering in manganite has attracted much interest in recent years. These studies have been possible from an experimental point of view by the third generation synchrotron sources. X-ray with high flux density, tunable energy and polarization can be produced in synchrotron sources. Experiments have shown a resonant in peak intensity originating from charge and orbital ordering when the incident photon energy matches the manganese K-edge energy. In this paper we have calculated the scattering factor and intensity of charge and orbital ordering reflections on the Mn K-edge energy in Nd0.5Sr0.5MnO3 on the basis of its structure and the chosen model of charge and orbital ordering. The energy and azimuthal angle dependence of the peaks intensity have been investigated and compared with the experimental results.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
43
51
http://ijpr.iut.ac.ir/article_565_0e6917e26a73623b64cd283566c6ca63.pdf
Statistical analysis of heart beat time series
F. Atiyabi
author
M. Akbari Livari
author
K. Kaviani
author
text
article
2019
per
In this paper, we study the statistical approaches to diagnose the heart by using the heart rate of individuals. First we review some well known methods and then we consider two new approaches. We analyse the extended self-similarity (ESS) and recursive model in the beat-to-beat fluctuations in the heart rates of healthy subjects as well as those with congestive heart failure. These concepts provide two novel techniques for distinguishing the two classes of subjects
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
53
59
http://ijpr.iut.ac.ir/article_566_225bb6077b719bbd9e4604634cfaa5dd.pdf
Ab-initio study of the structural, magnetic and electric properties of NixCr1-x x={0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875}
R. Golsorkhtabar
author
S. J. Hashemifar
author
H. Akbarzadeh
author
text
article
2019
per
We investigated the structural, magnetic and electronic properties of NixCr1-x alloy in the range 0.125≤ x ≤0.875 by using FP-LAPW method to solve Kohn-Sham equations. In structural study, we calculated the formation energy, lattice parameter and bulk modulus for bcc and fcc structures within ferromagnetic, ferromagnetic and paramagnetic phases. Our results indicate that the system preference for alloy formation is higher in the range of x=0.625 – 0.75 compared to other studied concentrations. Moreover, by investigation of the values obtained for the lattice parameter and bulk modulus we found out that Cr-Ni bond is weaker than Ni-Ni and Cr-Cr bonds. Additionally, our magnetic results indicate that the magnetic interactions among atoms in bcc structures have probably RKKY behavior. Finally, our results show that the Ni0.75Cr0.25 alloy with fcc structure ans spin polarization of 90% has the highest magnetic and structural stability.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
7
v.
1
no.
2019
61
72
http://ijpr.iut.ac.ir/article_567_3c0fb86af424dcb837f10c44a7884fd0.pdf