Nuclear Science Research School

Tehrān, Iran

Nuclear Science Research School

Tehrān, Iran
Time filter
Source Type

Hatam E.G.,Jozef Stefan Institute | Hatam E.G.,Nuclear Science Research School | Pelicon P.,Jozef Stefan Institute | Lamehi-Rachti M.,Nuclear Science Research School | And 5 more authors.
Journal of Analytical Atomic Spectrometry | Year: 2012

A method of sample surface topography reconstruction is described based on the asymmetry in the X-ray yields acquired by a pair of X-ray detectors positioned at opposite sides of the probing beam. The yield asymmetries in the two simultaneously acquired elemental maps are caused by differences in the X-ray absorption along the X-ray exit route in the sample with a topographically structured surface. The approach presented introduces an asymmetry factor of the X-ray intensity in each of the image pixels to obtain an image asymmetry matrix. The dependence of the asymmetry factor on the local target inclination in the detector plane is calculated for a flat sample surface model. The image asymmetry matrix is then converted into the local inclination angle matrix. As the last step, the surface topography is then reconstructed from the local inclination angle. The method is based on X-ray absorption phenomena and could be applied equivalently in X-ray elemental mapping methods using excitation beams with a well-defined direction in the sample. This includes micro-X-Ray Fluorescence analysis (micro-XRF) and micro-Proton Induced X-ray Emission (micro-PIXE). We demonstrated the method by topographic analysis of engraved metallic samples with stereo-PIXE and compared it with the results of stylus profilometry. The smallest value of the X-ray production depth and the characteristic X-ray attenuation length determines the lateral resolution of the proposed topography reconstruction method. © 2012 The Royal Society of Chemistry.

Maragheh M.G.,Nuclear Science Research School
International Journal of Refractory Metals and Hard Materials | Year: 2016

In this study, the dispersing phenomenon of titanium carbide suspensions has been investigated using various dispersants. The effect of pH and dispersant concentration on the dispersibility of the powder has been studied via sedimentation and zeta potential test. To optimize the pH range for the best dispersibility, the sedimentation test has been carried out in various dispersant concentrations in wide pH range. The zeta potential of TiC suspensions, both with and without polyelectrolyte addition, is examined as a function of pH. Zeta potential studies show that the isoelectric point of TiC powder is at pH 3.1. The use of an anionic polyelectrolyte, tetramethylammonium hydroxide in the optimum concentration, significantly increased the stability of suspension. The maximum value of the zeta potential - 60 mV is obtained in 0.4 wt.% at pH 8. The addition of a cationic dispersant, polyethylenimine, significantly alters the isoelectric point and shifts to the basic pH. The maximum stability of suspension was achieved in 2 wt.% at pH 8. The result showed that nonionic dispersant polyethylene glycol 400 is not a good dispersant for TiC suspension. The surface charge and potential do not change in the presence of this dispersant. © 2015 Elsevier Ltd. All rights reserved.

Pishkoo A.,Nuclear Science Research School | Pashaei R.,Islamic Azad University at Tehran
Journal of Computational and Theoretical Nanoscience | Year: 2015

Using Laplacian operator in f-dimensional fractional space in three-spatial coordinates, in this paper the reaction-Diffusion equation is solved for fractal (porous) domains. Our previous work had focused on how Meijer's G-functions are deduced as the solutions of the Reaction-Diffusion process in making Micro- and Nano-structures with assumption being in ordinary (not fractional) space. However, in porous domains some of the regions or domains are not filled with medium particles so to describe appropriately these regions the fractional model is needed. We express the solution of reaction-diffusion equation in cylindrical coordinates system in terms of elementary and Meijer's G-functions. Copyright © 2015 American Scientific Publishers All rights reserved.

Torkiha M.,Institute for Studies in Theoretical Physics and Mathematics IPM | Lamehi-Rachti M.,Nuclear Science Research School | Kakuee O.R.,Nuclear Science Research School | Fathollahi V.,Nuclear Science Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2010

A simple and compact electrostatic quadrupole triplet lens has been designed and fabricated as part of the dedicated beam line for analysis of archaeological samples. A Fortran based ion optics program has been developed to simulate the beam line and lens parameters to achieve a focused sub-millimeter beam spot. The results of simulations are utilized to design and fabricate beam-line elements. The beam spot was measured by wire scanning method to be 0.3 mm for the object-slit width of 1 mm at a distance of 15 mm from the exit window. The improved Ion Beam Analysis setup allows accelerated PIXE analysis of samples whose details are comparable with the beam probe in size. The PIXE spectrum obtained by external analysis of a historical enameled ceramic sample with a sub-millimeter beam is compared with that obtained by in-vacuum standard PIXE analysis. © 2010 Elsevier B.V. All rights reserved.

Tajik M.,Damghan University | Tajik M.,Nuclear Science Research School | Ghal-Eh N.,Damghan University | Etaati G.R.,University of Tehran | Afarideh H.,University of Tehran
Radiation Physics and Chemistry | Year: 2014

The response of an NE213 (or its BICRON equivalent, BC501A) scintillator attached to different sizes of polished/painted lightguides when exposed to 241Am-Be neutrons has been simulated. This kind of simulation basically needs both particle and light transports: the transport of neutrons and neutron-induced charged particles such as alphas, protons, carbon nuclei and so on has been undertaken using MCNPX whilst the scintillation light transport has been performed with PHOTRACK codes. The comparison between simulated and experimental response functions of NE213 attached to different sizes of polished/painted lightguides and also the influence of length/covering of lightguide on the detection efficiency and uniformity of the scintillator-lightguide assembly response have been studied. © 2013 Elsevier Ltd.

Deevband M.R.,University of Tehran | Abdolmaleki P.,University of Tehran | Kardan M.R.,Nuclear science Research School | Khosravi H.R.,Nuclear Science and Technology Research Institute, Iran | Taheri M.,Nuclear science Research School
Applied Radiation and Isotopes | Year: 2011

The response of PADC was calculated by Monte Carlo simulation using MCNPX code. H, C and O recoils as well as nuclear reactions have been taken into account. The calculated results show important contribution to detection efficiency of PADC due to H, C and O recoils. The irradiated detectors with 241Am-Be source and 241Am-Be softened with a spherical polyethylene moderator were electrochemically etched. The paper presents the results of the experimental and Monte Carlo simulations, which are in a good agreement. © 2010 Elsevier Ltd.

Tajik M.,Nuclear Science Research School | Tajik M.,Damghan University | Ghal-Eh N.,Damghan University | Etaati G.R.,University of Tehran | Afarideh H.,University of Tehran
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

This paper reports on how to generate the response function of an NE213 scintillator when exposed to mono-energetic neutrons using the PTRAC card of the MCNPX code. The light transport part of the simulation has been undertaken with the Monte Carlo PHOTRACK code. The comparison confirms that the simulated response function represents a promising agreement with the previously published simulations and experiments. © 2012 Elsevier B.V.

Kakuee O.,Nuclear Science Research School | Fathollahi V.,Nuclear Science Research School | Oliaiy P.,Nuclear Science Research School | Lamehi-Rachti M.,Nuclear Science Research School | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

The paints of illumination, ink and paper of an Iranian poetry manuscript originally belonging to 15th century but partly restored about 300 years ago are characterized by external PIXE. The technique was employed to determine the elemental composition of different inks and paints applied in the text and illumination as well as the paper of both the original masterpiece and the restored parts in order to evaluate the quality of restoration processes. The X-ray spectra were collected by a Si(Li) X-ray detector placed at a scattering angle of 135° while the beam charge was indirectly measured through the Ar K α X-ray yield originated from the irradiation of in-air Argon. By analysis of the collected PIXE spectra, concentration of different elements present in closely matched colored areas in the original and restored illuminations were compared. In the same way, the origin of colored pigments and black ink in the original and restored illuminations and texts are inferred. © 2011 Elsevier B.V. All rights reserved.

Amiri M.,Nuclear Science Research School | Farzin L.,Nuclear Science Research School | Moassesi M.E.,Nuclear Science Research School | Sajadi F.,Nuclear Science Research School
Biological Trace Element Research | Year: 2010

Febrile convulsion is the most common disorder in childhood with good prognosis. There are different hypotheses about neurotransmitters and trace element changes in biological fluids which can have a role in pathogenesis of febrile convulsion. In this study, serum selenium, zinc, and copper were measured by atomic absorption spectrometry in the children with febrile convulsion (n=30) and in the control group (n=30). The age and sex of the subjects were registered. Selenium and zinc were found to be significantly lower in febrile convulsion cases than in the control group (p<0.0001 and p<0.0001, respectively). There was no significant difference in the value of copper between the two groups (p=0.16). While selenium and zinc levels were 44.92±10.93 μg/l and 66.13±18.97 μg/dl in febrile convulsion, they were found to be 62.98±9.80 μg/l and 107.87±28.79 μg/dl in healthy children. Meanwhile, copper levels were 146.40±23.51 μg/dl in the patients and 137.63±24.19 μg/dl in the control group, respectively. This study shows that selenium and zinc play an important role in the pathogenesis of febrile convulsion. © 2009 Humana Press Inc.

Kakuee O.R.,Nuclear Science Research School | Fathollahi V.,Nuclear Science Research School | Rachti M.L.,Nuclear Science Research School
International Journal of Hydrogen Energy | Year: 2010

Hydrogen is considered to be the ideal energy carrier in the near future. It would be of great importance to obtain experimental data regarding the interaction of hydrogen with materials as they could assist to better realize the occurring phenomena. More specifically, quantification of hydrogen in materials could help to modify the materials processing conditions in the field of hydrogen generation, storage and utilization for the final goal of energy generation. Measurement of hydrogen in materials has always been a challenge in front of researchers. In this research work, hydrogen analysis has been performed by "Elastic Recoil Detection" (ERD) technique using the α-beam of the Van de Graaff accelerator of Nuclear Science and Technology Research Institute (NSTRI). Capability of ERD for quantification of hydrogen in carbon nanotube, H-treated Ti thin layer as well as in semiconducting sample of Si single crystal - prepared under certain conditions - has been shown. Capability of ERD for characterization of advanced materials is shown by hydrogen quantification or hydrogen concentration depth profiling in each representative example. © 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Loading Nuclear Science Research School collaborators
Loading Nuclear Science Research School collaborators