Physics and Accelerators Research School

Iran

Physics and Accelerators Research School

Iran
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Dashti-Naserabadi H.,Physics and Accelerators Research School | Saberi A.A.,University of Tehran | Saberi A.A.,Institute for Research in Fundamental Sciences | Rouhani S.,Institute for Research in Fundamental Sciences | Rouhani S.,Sharif University of Technology
New Journal of Physics | Year: 2017

We study (2+1)-dimensional single step model for crystal growth including both deposition and evaporation processes parametrized by a single control parameter p. Using extensive numerical simulations with a relatively high statistics, we estimate various interface exponents such as roughness, growth and dynamic exponents as well as various geometric and distribution exponents of height clusters and their boundaries (or iso-height lines) as function of p. We find that, in contrary to the general belief, there exists a critical value at which the model undergoes a roughening transition from a rough phase with in the Kardar-Parisi-Zhang universality to a smooth phase with , asymptotically in the Edwards-Wilkinson class. We validate our conclusion by estimating the effective roughness exponents and their extrapolation to the infinite-size limit. © 2017 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Ameri B.,Shahid Beheshti University | Davarani S.S.H.,Shahid Beheshti University | Moazami H.R.,Physics and Accelerators Research School | Darjazi H.,NaghsheJahan Institute of Higher Education
Journal of Alloys and Compounds | Year: 2017

ZnMn2O4/Mn3O4 composite nanostructures were prepared by cathodic electrodeposition followed by heat treatment. A mixed hydroxide precursor was galvanostatically electrodeposited from aqueous solution containing Mn and Zn (as nitrates) and the obtained precursor was annealed to prepare the composite. This composite exhibited much better electrochemical behaviors than bare Mn3O4. Rietveld analysis of the X-ray diffraction (XRD) data showed that the product was composed of Mn3O4, ZnMn2O4 and minor amounts of λ-MnO2. Furthermore, the obtained composite was characterized by Fourier transform infrared spectrometry (FT-IR) and energy dispersive spectrometry (EDS). Field emission scanning electron micrographs (FE-SEM) and transmission electron micrographs (TEM) revealed co-existence of nanoparticles and high aspect ratio nanorods. Electrochemical performance and ion transport of ZnMn2O4/Mn3O4 composite were studied via galvanostatic charge-discharge (GCD) cycling and electrochemical impedance spectroscopy (EIS). Cyclic voltammetric (CV) measurements showed a maximum specific capacitance of 321.34 F/g at the scan rate of 1 mV/s. 93% of this specific capacitance was retained after 2000 cycles. © 2017 Elsevier B.V.


Pishkoo A.,Physics and Accelerators Research School | Darus M.,National University of Malaysia
Journal of Computational and Theoretical Nanoscience | Year: 2015

Spectroscopy is a powerful technique to study vibrational, rotational, and other low frequency modes in a physical system. This study will address the following research question: To occur transition from ground state to excited state in Hydrogen atom, which intermediate states do electrons pass through from? An excited atom is unstable and tends to rearrange itself to return to its lowest energy state. In other words, which analytic function can describe these intermediate states from ground state to excited state (absorption) and vice versa (emission)? We show that Meijer G-function can be used to represent these intermediate states by introducing the fractional Bohr operator. © 2015 American Scientific Publishers.


Mohammadi J.,Shahid Beheshti University | Davarani S.S.H.,Shahid Beheshti University | Moazami H.R.,Physics and Accelerators Research School
Analytica Chimica Acta | Year: 2016

Electromembrane extraction (EME) was carried out using a novel instrumentation capable of impedometric monitoring of the system during the extraction. This instrumentation involves a classical two-electrode assembly fed by two time-resolved potential functions, the first for the extraction of analyte and the second for obtaining the impedance information. The impedometric analysis of the system was achieved by Laplace transformation of the current recorded during the extraction. It has been shown that the obtained impedance information can be converted to very useful knowledge about time dependence of double layer capacitance, kinetics of analyte depletion, total permeability of the SLM and the effect of experimental parameters on system behavior. It has also been shown that the impedance analysis is a powerful tool for the estimation of optimum experimental parameters without determination of analyte in the acceptor phase. © 2016 Elsevier B.V.


Jokar A.,Physics and Accelerators Research School | Kakuee O.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

In this research work, measured differential cross sections for gamma-ray emission from the nuclear reactions 35Cl(d,pγ1-0)36Cl (Eγ = 788 keV), 35Cl(d,pγ2-0)36Cl (Eγ = 1165 keV), 37Cl(d,pγ1-0)38Cl (Eγ = 671 keV) and 37Cl(d,pγ2-0)38Cl (Eγ = 755 keV) are presented. For these measurements a thin natural BaCl2 target evaporated onto a 50 μm-thick Mo foil was used. The gamma-rays and backscattered deuterons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to the beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered deuterons. The validity of the obtained differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of cross section values was estimated to be ±10%. © 2016 Elsevier B.V. All rights reserved.


Rafi-Kheiri H.,Physics and Accelerators Research School | Kakuee O.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

Differential cross sections of the 24Mg(d,p0,1,2,3,4) reactions were obtained in the range Ed,lab = 1.2-2 MeV and at the scattering angles of 90°, 135°, 150° and 165° using a thin Mg target having thickness of 76.7 ± 3.1 μg/cm2. The cross section values were determined with an average energy step of ∼25 keV while the detailed measurements were carried out with an energy step of ∼5 keV around the resonance peaks. Elastic scattering data for three steep backward angles (135°, 150° and 165°) were also studied for the same incident deuteron energy range and steps. The results were compared with those of the previous studies. Moreover, the validity of the measured data has been benchmarked using a thick Mg target at two deuteron beam energies of 1.7 and 2 MeV. © 2016 Elsevier B.V. All rights reserved.


Rafi-Kheiri H.,Physics and Accelerators Research School | Kakuee O.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

In the present work, differential cross section values of the 16O(d,d0) reaction were obtained for Ed,lab = 900-2000 keV, at four scattering angles, namely at 90°, 135°, 150° and 165° using a thin SiO target having a thickness of (910 ± 36) × 1015 at/cm2. The cross section values were determined with an energy step of ∼10 keV while, the detailed measurements were carried out with an energy step of ∼5 keV around the resonance peaks. The results were compared with those of the previous studies. © 2016 Elsevier B.V. All rights reserved.


Jokar A.,Physics and Accelerators Research School | Kakuee O.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

Differential cross sections for gamma-ray emission from the 28Si(p,p/γ)28Si (Eγ = 1779 keV) and the 29Si(p,p/γ)29Si (Eγ = 1273 keV) nuclear reactions were measured in the energy range of 2.0-3.2 MeV and 2.0-3.0 MeV, respectively. The thin Si targets were prepared by evaporating natural SiO onto self-supporting Ag films. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. The great advantage of this work is that differential cross sections were obtained with a procedure irrespective of absolute value of the collected beam charge. © 2015 Elsevier B.V. All rights reserved.


Rafi-Kheiri H.,Physics and Accelerators Research School | Kakuee O.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

Nuclear Reaction Analysis (NRA) and more specifically d-NRA is a suitable technique for 16O detection on or near surface of a compound containing heavy elements. The main problem of d-NRA is the limited number of NRA differential cross section data sets and their differences. The differential cross sections of 16O(d,p0,1) reactions were measured in the present work for Ed,lab = 700-1800 keV, at four scattering angles, namely at 90°, 135°, 150° and 165° which are suitable for NRA. Differential cross sections were collected with an energy step of ∼10 keV. However, detailed measurements were carried out with an energy step of ∼2 keV around resonances. The results are compared with previous studies and the similarities and differences are discussed. © 2015 Elsevier B.V. All rights reserved.


Kakuee O.,Physics and Accelerators Research School | Fathollahi V.,Physics and Accelerators Research School | Lamehi-Rachti M.,Physics and Accelerators Research School
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

Reliable performance of the Ion Beam Analysis (IBA) techniques is based on the accurate geometry of the experimental setup, employment of the reliable nuclear data and implementation of dedicated analysis software for each of the IBA techniques. It has already been shown that geometrical imperfections lead to significant uncertainties in quantifications of IBA measurements. To minimize these uncertainties, a user-friendly experimental chamber with a heuristic sample positioning system for IBA analysis was recently developed in the Van de Graaff laboratory in Tehran. This system enhances IBA capabilities and in particular Nuclear Reaction Analysis (NRA) and Elastic Recoil Detection Analysis (ERDA) techniques. The newly developed sample manipulator provides the possibility of both controlling the tilt angle of the sample and analyzing samples with different thicknesses. Moreover, a reasonable number of samples can be loaded in the sample wheel. A comparison of the measured cross section data of the 16O(d,p1)17O reaction with the data reported in the literature confirms the performance and capability of the newly developed experimental chamber. © 2015 Elsevier B.V.

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