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EGRET unidentified sources and the galactic spiral arms
, Article 5th INTEGRAL Workshop on The INTEGRAL Universe, Munich, 16 February 2004 through 20 February 2004 ; Issue 552 , 2004 , Pages 695-698 ; 03796566 (ISSN) ; Bhattacharya, D ; Zych, A ; Akyuz, A ; Samimi, J ; Sharif University of Technology
2004
Abstract
An unbiased and complete LogN-LogS relation samples the source distribution for a specific source geometry without the knowledge of the source luminosity function or the distance. Based on such an analysis we show that EGRET unidentified (EUI) sources are very closely aligned with the Galactic spiral arms and specifically with the distribution of the giant molecular clouds. Furthermore, the luminosity distribution of the unidentified sources show a two population Gaussian distribution. We find that a combined distribution of OB associations, SNR and superbubbles interacting with molecular clouds within the spiral arms are the most likely counterparts of the unidentified sources
SGSD: A novel Sequential Gamma-ray Spectrum Deconvolution algorithm
, Article Annals of Nuclear Energy ; Volume 132 , 2019 , Pages 369-380 ; 03064549 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A novel approach for analyzing complex gamma-ray spectra using a sequential algorithm is introduced. The developed Sequential Gamma-ray Spectrum Deconvolution (SGSD)algorithm produces a sequence of spectra converging to the best estimation of output spectrum of a gamma-ray detector. In each point of sequence, an isotope of unknown gamma-ray source is identified and the respective response of the detector to unknown source is reconstructed. Effectiveness of the developed algorithm is demonstrated by two empirical and simulation studies. In the case of empirical study, a number of recorded gamma-ray spectra related to a mixed gamma-ray source including different combinations of 5 isotopes...
Evaluation the nonlinear response function of a HPGe detector for 59 keV to 10.7 MeV gamma-rays using a Monte Carlo simulation and comparison with experimental data
, Article Journal of Instrumentation ; Volume 16, Issue 7 , 2021 ; 17480221 (ISSN) ; Riazi, Z ; Jokar, A ; Shahabinejad, H ; Vosoughi, N ; Ghasemi, S. A ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Modeling of High Purity Germanium (HPGe) detector on a wide energy range is important in gamma-ray spectroscopy. The precisely modeled detector can be used for proton-induced prompt gamma-ray spectroscopy. In this work, we used both the gamma-rays of calibration sources and prompt gamma-rays emitted in proton capture reactions to model a coaxial p-type HPGe detector using Geant4 Monte Carlo simulation for the gamma-ray energy range of 59–10764 keV. The calibration sources were 137Cs, 241Am, 60Co, 152Eu, and 133Ba, while the prompt gamma-rays were due to the gamma-ray cascades following the 27Al(p,γ)28Si reaction capture at the resonant energies of 992, 1317 and 2483 keV, as well as the...
Enhanced performance of an electron tracking Compton gamma-ray telescope
, Article New Astronomy ; Volume 9, Issue 2 , 2004 , Pages 127-135 ; 13841076 (ISSN) ; Bhattacharya, D ; O'Neill, T. J ; Samimi, J ; Zych, A ; Sharif University of Technology
2004
Abstract
TIGRE, the UCR Compton gamma-ray telescope, is designed to make use of the Compton recoil electron track to improve the flux sensitivity in the medium gamma-ray energy range (0.4-100 MeV). TIGRE uses multilayers of silicon strip detectors to track Compton scattered electrons, and CsI detectors to measure the scattered photon energy and direction. In this work, using Monte-Carlo simulation, we show the improvement that can be obtained when the electron tracking feature is added to a conventional Compton telescope. In simulating a Crab-like source in a balloon-background environment, the flux sensitivity for TIGRE is enhanced by a factor of 2.5 and the source location accuracy by a factor 3...
On the distribution of EGRET unidentified sources in the Galactic plane
, Article Astronomy and Astrophysics ; Volume 404, Issue 1 , 2003 , Pages 163-170 ; 00046361 (ISSN) ; Akyüz, A ; Miyagi, T ; Samimi, J ; Zych, A ; Sharif University of Technology
EDP Sciences
2003
Abstract
It has been suggested that young pulsars, with ages less than a million years, are possible counterparts of some of the Galactic unidentified gamma-ray sources detected by the EGRET instrument on-board the Compton Gamma Ray Observatory. In this work, we compare different aspects of the EGRET unidentified (EUI) source distribution in the Galactic plane with those of the pulsar distribution. An EUI source Log N-Log S analysis is presented and compared with the Galactic radio pulsar Log N-Log S distribution. A number of systematic effects that could introduce errors to the EGRET Log N-Log S relation are discussed. A two-point angular correlation analysis of the EUI sources and Galactic pulsars...
Observation of EGRET gamma-ray sources by an extensive air shower experiment
, Article Astronomy and Astrophysics ; Volume 434, Issue 2 , 2005 , Pages 459-467 ; 00046361 (ISSN) ; Bahmanabadi, M ; Samimi, J ; Sharif University of Technology
2005
Abstract
Ultra-high-energy (E > 100 TeV) Extensive Air Showers (EASs) have been monitored for a period of five years (1997-2003), using a small array of scintillator detectors in Tehran, Iran. The data have been analyzed taking into account the dependence of source counts on zenith angle. During a calendar year different sources come into the field of view of the detector at varying zenith angles. Because of varying thickness of the overlaying atmosphere, the shower count rate is extremely dependent on zenith angle, which has been carefully analyzed over time (Bahmanabadi et al. 2002, Exp. Astron., 13, 39). High energy gamma-ray sources from the EGRET third catalogue where observed and the data were...
Analysis of complex gamma-ray spectra using particle swarm optimization
, Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ; Volume 911 , 2018 , Pages 123-130 ; 01689002 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Analysis of gamma-ray spectra is an important step for identification and quantification of radionuclides in a sample. In this paper a new gamma-ray spectra analysis algorithm based on Particle Swarm Optimization (PSO) is developed to identify different isotopes of a mixed gamma-ray source and determine their fractional abundances. PSO is an iterative algorithm that imitates the social behaviors observed in nature to solve complex optimization problems. The PSO method is used for complex fitting to the response of a 3 [Formula presented] 3 inch NaI (Tl) scintillation detector and the fitting process is controlled by a test for significance of abundance and computation of Theil coefficient....
Finding gamma ray events by the method of obtaining poisson distribution from data collected by an array of Cherenkov detectors
, Article 31st International Cosmic Ray Conference, ICRC 2009, 7 July 2009 through 15 July 2009, Lodz ; 2009 ; Qomi, M. K ; Samimi, J ; Hamedivafa, H ; Sheidaei, F ; Bahmanabadi, M ; Sharif University of Technology
Abstract
a small array of Water Cherenkov Detectors (WCDs) has recorded 600000 events related to extensive air showers in Tehran during one year at an altitude of 1200m. By employing the method of obtaining count in each time interval distributions we obtained the distribution of extensive air showers. 17 events were found in our data set which are more probable to be related to primary gamma ray photons. For more certainty we did a simulation to compare acquired results from simulation and data to become sure if 17 extensive air showers are electromagnetic or not
Investigation of the gamma-ray shielding performance of the B2O3-Bi2O3-ZnO-Li2O glasses based on the monte carlo approach
, Article Radiation Physics and Chemistry ; Volume 189 , 2021 ; 0969806X (ISSN) ; Hosseini, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The purpose of this article is to investigate the shielding performance of the B2O3-Bi2O3-ZnO-Li2O glasses against the gamma-ray. To this end, the attenuation parameters of the gamma-ray inside the B2O3-Bi2O3-ZnO-Li2O glasses were evaluated in the energy range of 200–1500 keV. It was found that the mass attenuation coefficient of the composites increases with increasing the Li2O content. The relative percent deviation between the results of simulation using the MCNPX and XCOM database in most cases was less than 2%. Additionally, the Mean Free Path (MFP) and Half-Value Layer (HVL) parameters were evaluated, and the shielding efficiency of samples was compared with some conventional shielding...
Investigation of EGRET gamma-ray sources by an extensive air shower experiment
, Article 29th International Cosmic Ray Conference, ICRC 2005, Pune, 3 August 2005 through 10 August 2005 ; Volume 6 , 2005 , Pages 29-32 ; Samimi, J ; Bahmanabadi, M ; Sharif University of Technology
Tata Institute of Fundamental Research
2005
Abstract
Ultra-high-energy ( E ≥ TeV) Extensive Air Showers (EASs) have been monitored for a period of five years (1997-2003 ), using a small array of scintillator detectors in Tehran, Iran. The data have been analyzed to take in to account of the dependence of source counts on zenith angle. During a calendar year different sources come in the field of view of the detector at varying zenith angles. Because of varying thickness of the overlaying atmosphere, the shower count rate is extremely dependent on zenith angle which have been carefully analyzed over time. High energy gamma-ray sources from the EGRET third catalogue where observed and the data were analyzed using an excess method. Upper limits...
Imprints of gravitational millilensing on the light curve of gamma-ray bursts
, Article Astrophysical Journal ; Volume 922, Issue 1 , November , 2021 ; 0004637X (ISSN) ; Ibrahim, A ; Reza Rahimi Tabar, M ; Rahvar, S ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
In this work, we search for signatures of gravitational millilensing in gamma-ray bursts (GRBs) in which the source-lens-observer geometry produces two images that manifest in the GRB light curve as superimposed peaks with identical temporal variability (or echoes), separated by the time delay between the two images. According to the sensitivity of our detection method, we consider millilensing events due to point-mass lenses in the range of 105 - 107 M o˙ at lens redshift about half that of the GRB, with a time delay on the order of 10 s. Current GRB observatories are capable of resolving and constraining this lensing scenario if the above conditions are met. We investigated the Fermi/GBM...
Discrimination between gamma and proton-induced showers using the parabolic shape of the air shower front
, Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ; Volume 1042 , 2022 ; 01689002 (ISSN) ; Bahmanabadi, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
It was used CORSIKA simulations to investigate the characteristics of showers with energies comprised between 1014–1016eV. All simulations were performed for an altitude of 1200 m above sea level (altitude of Alborz Observatory at Tehran). By fitting the parabolic curve on the air shower front, its focal length can be obtained. The results of this study show that the focal length of the air shower front of gamma rays is separable from cosmic protons and this can be used as a hybrid for other methods of separating the two kind particles from each other. © 2022
Preparation of PLA and CNT Nanocomposites and Investigation of Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Polylactic acid (PLA) is a biocompatible polymer that could be used for biomedical applications. Carbon nanotubes (CNT) have excellent mechanical strength and modulus and also are electrically conductive. Inclusion of CNT in PLA could improve mechanical and electrical properties of PLA and find applications as biomaterials in biomedical engineering. The success of the resulted nanocomposites of PLA/CNT depends on uniform dispersion of CNT within PLA and good interfacial adhesion between the nanotubes and the matrix PLA. Chemical modification of CNT surface by grafting maleic anhydride has been reported. However, for biomedical applications chemical agents may prove harmful and should be...
Search for Gamma-Ray events in ALBORZ observatory data
, Article 31st International Cosmic Ray Conference, ICRC 2009, Lodz, 7 July 2009 through 15 July 2009 ; 2009 ; Bayesteh, S ; Bahmanabadi, M ; Hedayati, H ; Sheidaei, F ; Anvari, A ; Samimi, J ; Sharif University of Technology
University of Lodz
2009
Abstract
At ALBORZ Observatory in Tehran (51° 200 , 35 ° 430' , 1200 m) we accumulated a complete year of data by a 4-fold square array of Water Cherenkov Detectors (WCDs) with the side 6.08 m. It is recorded about 800,000 fine EAS events from 2006/11/12 to 2007/11/20 by the approximate recording rate of 0.03. Time differences between each two, three, four, five and ... have a very good agreement with gammafunction, which shows the correct random nature of the events. Of course we expect that about less than 1% of the EAS events (≤9000 events) be electromagnetic and naturally not random, but the contribution is so small. Then by Farley/Storey procedure [1] we found a signature of real sidereal data....
Poly (vinyl alcohol)/graphene oxide nanocomposite films and hydrogels prepared by gamma ray
, Article Plastics, Rubber and Composites ; Volume 48, Issue 2 , 2019 , Pages 42-47 ; 14658011 (ISSN) ; Dadbin, S ; Tabatabaei, M ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Poly (vinyl alcohol)/graphene oxide (PVA/GO) gamma irradiated nanocomposite films and hydrogels were prepared. In composite films, GO was initially irradiated by gamma ray in order to improve interactions between GO and PVA. The film containing 1 wt-% GO was very strong where tensile modulus and tensile yield strength were 45 and 115% higher than those of pure PVA. In the second set of experiments PVA/GO hydrogels were made by irradiating PVA/GO suspensions by gamma ray at various doses. It was an interesting finding that GO increased the gel portion of hydrogels through contribution of H-bonds between PVA and GO. The hydrogels prepared at 20 kGy had remarkable water swelling ratio that...
Gamma irradiated electro-conductive polylactic acid/polyaniline nanofibers
, Article Synthetic Metals ; Volume 259 , 2020 ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, polyaniline nanoparticles (PANI NPs) in emeraldine base (EB) form were prepared by a modified method and characterized by FTIR and UV–vis spectroscopies. The average size of the nanoparticles was 140 nm measured by DLS method. The nanoparticles were embedded into polylactic acid (PLA) nanofibers prepared by electrospinning method. It was found that inclusion of PANI NPs in PLA resulted in reduced diameter of the fibers during the electrospinning process. Also, the surface of nanofibers appeared smooth in FE-SEM images without formation of beads. Improvement in mechanical and electrical properties of PLA/PANI nanofibers over the neat PLA nanofibers implied a good dispersion of...
Electrically Conductive Fibers and Films Based on PLA and Nano PANI
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Nowadays, the use of processed conductive polymers for conducting matrix polymers, as well as improving other properties for planting in the body, is very common. In this project, the fabrication and identification of electrically conductive films and fibers from biocompatible poly lactic acid and conductive polyAniline polymer in the form of nano-fibers or nanoparticles was intended. These fibers and films have been made in form of a plate or tube then, have been used as biosensors. These polymeric prostheses should be sterilized before planting in human body. Gamma rays are the best sterilization methods and are used at low doses (25 kGy) to sterilize plastic medical supplies. On the other...
Preparation of Antibacterial Silver, PVA, Na Alginate Nanocomposites Via Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
In this research, polyvinyl alcohol/ sodium alginate/ nano silver nanocomposite films were fabricated by solution casting method via gamma irradiation. The purpose of using gamma radiation was reduction of silver nitrate and synthesis of silver nanoparticles. Formation of silver nanoparticles was proved by ultra violet- visible spectroscopy (UV-Vis) and x-ray diffraction (XRD) tests. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) were used to study morphology, size and distribution of silver nanoparticles. Chemical structure, thermal behavior and mechanical properties of nanocomposites were characterized by fourier transform infrared spectroscopy (FTIR), differential...
Chemical corrosion and gamma-ray attenuation properties of Zr and Ti containing lead silicate glasses
, Article Journal of Nuclear Materials ; Volume 385, Issue 3 , 2009 , Pages 527-532 ; 00223115 (ISSN) ; Raisali, G ; Sadrnezhaad, K ; Alipour, A ; Sharif University of Technology
2009
Abstract
Lead silicate glasses (LSGs) have high gamma-ray attenuation but low chemical durability properties. In this work, LSGs with (55.5-68.5 wt%) PbO content containing ZrO2 and TiO2 additions were produced. The chemical corrosion of various produced LSGs in 0.5 N HNO3 aqueous solution and determination of their gamma-ray attenuation coefficients for 60Co and 137Cs sources were investigated. The weight loss measurements, the SEM micrographs, the EDS analysis of the sample surfaces and the ICP analysis of solution were used to characterize the dissolution process. The effects of PbO content, ZrO2 and TiO2 additives on chemical corrosion, and also the effect of PbO on gamma-ray attenuation...
Development of an experimental method based on Compton backscattering to measure the wax thickness in petroleum pipelines
, Article Journal of Instrumentation ; Volume 16, Issue 10 , 2021 ; 17480221 (ISSN) ; Taheri, A ; Askari, M ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Wax deposition inside pipelines is a major concern in oil and gas industries, and it must be continuously monitored. In this paper, a mathematical-experimental combined method based on the Compton scattering was proposed to determine the thickness of the wax deposited inside the industrial pipes. For this purpose, first, the relationship between the intensity of the backscattered gamma-rays and the thickness of the wax inside the pipe was mathematically modeled. Then, an experimental setup was prepared for measuring the intensity of the backscattered gamma-rays from the pipes with different wall thicknesses and different wax widths. Finally, the experimentally measured counts were used by...