Beam neutron energy optimization for boron neutron capture therapy using Monte Carlo method
Ali Pazirandeh
author
Elham Shekarian
author
text
article
2019
per
In last two decades the optimal neutron energy for the treatment of deep seated tumors in boron neutron capture therapy in view of neutron physics and chemical compounds of boron carrier has been under thorough study. Although neutron absorption cross section of boron is high (3836b), the treatment of deep seated tumors such as gliobelastoma multiform (GBM) requires beam of neutrons of higher energy that can penetrate deeply into the brain and thermalize in the proximity of the tumor. Dosage from recoil proton associated with fast neutrons however poses some constraints on maximum neutron energy that can be used in the treatment. For this reason neutrons in the epithermal energy range of 10eV-10keV are generally to be the most appropriate. The simulation carried out by Monte Carlo methods using MCBNCT and MCNP4C codes along with the cross section library in 290 groups extracted from ENDF/B6 main library. The optimal neutron energy for deep seated tumors depends on the size and depth of tumor. Our estimated optimized energy for the tumor of 5cm wide and 1-2cm thick stands at 5cm depth is in the range of 3-5keV
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
55
65
http://ijpr.iut.ac.ir/article_518_138ab1a438395dc466e3b80889e518c4.pdf
Generation of the large scale magnetic fields by coupling to curvature and dilaton field
A. Akhtari Zavareh
author
B. Mirza
author
A. Hojjati
author
text
article
2019
per
We investigate the generation of large scale magnetic fields in the universe from quantum fluctuations that are produced in the inflationary stage. By coupling these quantum fluctuations to the dilaton field and Ricci scalar, we show that the magnetic fields with the strength observed today can be produced. We consider two situations. First, the evolution of dilaton ends by starting the reheating stage. Second, the dilaton continues its evolution after reheating and then decays. We here consider the first case. In both cases, we come back to the usual Maxwell equations after inflation and then calculate present magnetic fields.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
67
76
http://ijpr.iut.ac.ir/article_519_293c50c115e14cef623288301f13d6f8.pdf
Magnetic properties of FeCo nanoparticles for information storage
S. A. Sebt
author
F. Azarkharman
author
M. Amir-Hosseini
author
S. Zoriasatain
author
M. Akhavan
author
text
article
2019
per
Submicron FeCo magnetic grains with different percents of cobalt were grown in the presence of magnetic field. After omitting the excess ions and oxygen, heat treatment was performed and some samples were oriented in a polymer background in the presence of a magnetic field. The results of SEM, XRD, and magnetic measurements confirm the existence of induced magnetic anisotropy. As the strength of the magnetic field during the growth of Fe0.7Co0.3 grains increases, the coercively increases from 820 to 1600 Oe. Measurements of magnetization time variation of the samples show a linear correspondence between magnetic stability factor and coercivity. The magnetization of the oriented samples increases by 25%. Raising the coercivity of the medium is the main factor for increasing the capacity of magnetic information storage.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
77
86
http://ijpr.iut.ac.ir/article_520_c338abed058fd9070dd95d79c1be881d.pdf
Cosmic ray simulation and dependence of maximum air shower development (Hmax) on mass and energy of primaries temperature
G. Rastgarzadeh
author
text
article
2019
per
Monte Carlo simulation with CORSIKA code using QGSJET hadronic interaction model is applied on more than 5000 cosmic ray primaries to investigate dependence of maximum air shower development (Hmax) on mass and energy of primaries.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
87
94
http://ijpr.iut.ac.ir/article_521_35911810053da1aabeac559a712aa400.pdf
Study of the dynamics of cascade processes of muonic atoms by multi group method
S. Z. Kalantari
author
M. H. Pirahmadian
author
text
article
2019
per
Studies on exotic atoms are important in different ways. They are important for strong interaction with nucleus and the theory of QCD in low energies. They are also important in muon catalyzed fusion (µCF). Their properties can be revealed by studies on cascade of muonic atoms. In this paper, unlike the others, we do not consider the kinetic energy of muonic atoms, constant (the kinetic energy of muonic atoms can vary due to cascade processes). We have used multi group method. The energy dependence of the rates of collisional cascade processes can take into account by this method. In addition, the energy spectra of muonic atoms in the ground state are calculated. For this purpose we divided the energy spectrum to 10 groups, and then use the rate of external Auger effect, Coulomb de-excitation, muon transfer and elastic scattering to solve the dynamics of cascade processes in each group. These equations are coupled linear differential equations. To solve them we use the Runge-Kutta method in the fourth order. One of the conclusions of this paper is that, this energy spectrum is not Maxwellian distribution. Finally our results are compared with the results of the Monte-Carlo simulation.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
95
109
http://ijpr.iut.ac.ir/article_522_a612526c70f60bdbc51d7c16c59debd6.pdf
Fission fragment angular distribution in heavy ion induced fission
S. Soheyli
author
I. Ziaeian
author
text
article
2019
per
We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a) without neutron correction and b) with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the average emitted neutron from compound nuclei considering the best fit for each system.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
111
121
http://ijpr.iut.ac.ir/article_523_7db63104fb503b73d902267b48625554.pdf
Hyperfine interactions in USb2 crystal
A.
Fathi
author
S.
Asadabadi
author
M.
Goshtasbi Rad
author
text
article
2019
per
The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT) employing the augmented plane wave plus local orbital (APW+lo) method. We investigated the dependence of the nuclear quadruple interactions on the magnetic structure in USb2 compound. The investigation were performed applying the so called “band correlated” LDA+U theory self consistently. The self consistent LDA+U calculations were gradually added to the performed generalized gradient approximation (GGA) including scalar relativistic spin-orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
123
136
http://ijpr.iut.ac.ir/article_524_3970b2c16005f8e77fa8989ce5c266b9.pdf
Multifractal and deterended fluctuation analysis of heartbeat electrical signals ECG
A. N. Beni
author
B. Mirza
author
F. Shahbazi
author
A. Kazempour
author
text
article
2019
per
In recent years cardiac interbeat interval time series have been investigated by DFA and MF-DFA methods. In this paper instead of investigating cardiac interbeat interval time series, ECG signals are considered, it is shown that the normal and abnormal heart signals have different scaling relations.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
137
144
http://ijpr.iut.ac.ir/article_525_04bfd17a49a5d567f9d547382feb5dde.pdf
Spectrum of mesons and hyperfine dependence potentials
A. A. Rajabi
author
text
article
2019
per
In most models, mesons consist of quark -antiquark pairs moving in a confining potential. However, it would be interesting to consider the effect of an extra residual interaction by introducing the quark particles which contain a dependent spin and isospin. In the Chiral constituent quark model, the hyperfine part of the potential is provided by the interaction of the Goldstone bosons, which give rise to a spin- and isospin-dependent part that is crucial for the description of the spectrum for energies lower than 1.7 Gev. In this model we have, not only included the confinement potential at large separations but also the color charge as well as hyperfine interaction potentials. This combination of potentials yields meson spectra which are very close to the ones obtained in experiments.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
2
no.
2019
145
145
http://ijpr.iut.ac.ir/article_526_ac3bf878bc9bef95f6976976d4480fda.pdf