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Nasseri M.M.,Institute of Nuclear Science and Technology
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

Abstract The production of pyroelectric type X-ray generators has a long term background. In case of using X-ray generators containing two pyroelectric crystals, some parameters have not been practically measured yet. This article aims to calculate such parameters by means of Geant4 Mont Carlo codes. The obtained edge energy of initial electrons was 3 keV at a constant pressure of 1mTorr and electric field of 250 kV/cm. The amplification coefficient production of electrons was increased reaching to a constant value of 2.7. The observed mean energy of produced gas ions was approximately 39 eV, equivalent to 5.7% of the emitted electrons. The efficiency of the generated X-ray was about 63% and did not show a considerable change as the energy of initial electrons increased. © 2015 Elsevier B.V. Source


Cohen D.D.,Australian Nuclear Science and Technology Organisation | Crawford J.,Australian Nuclear Science and Technology Organisation | Stelcer E.,Australian Nuclear Science and Technology Organisation | Bac V.T.,Institute of Nuclear Science and Technology
Atmospheric Environment | Year: 2010

PM2.5 particulate matter has been collected on Teflon filters every Sunday and Wednesday at Hanoi, Vietnam for nearly eight years from April 2001 to December 2008. These filters have been analysed for over 21 different chemical species from hydrogen to lead by ion beam analysis techniques. This is the first long term PM2.5 dataset for this region. The average PM2.5 mass for the study period was (54 ± 33) μg m-3, well above the current US EPA health goal of 15 μg m-3. The average PM2.5 composition was found to be (29 ± 8)% ammonium sulfate, (8.9 ± 3.3)% soil, (28 ± 11)% organic matter, (0.6 ± 1.4)% salt and (9.2 ± 2.8)% black carbon. The remaining missing mass (25%) was mainly nitrates and absorbed water. Positive matrix factorisation techniques identified the major source contributions to the fine mass as automobiles and transport (40 ± 10)%, windblown soil (3.4 ± 2)%, secondary sulfates (7.8 ± 10)%, smoke from biomass burning (13 ± 6)%, ferrous and cement industries (19 ± 8)%, and coal combustion (17 ± 7)% during the 8 year study period. © 2009 Elsevier Ltd. Source


Cohen D.D.,Australian Nuclear Science and Technology Organisation | Crawford J.,Australian Nuclear Science and Technology Organisation | Stelcer E.,Australian Nuclear Science and Technology Organisation | Bac V.T.,Institute of Nuclear Science and Technology
Atmospheric Environment | Year: 2010

Fine particulate matter (PM2.5), source fingerprints and their contributions have been measured and reported previously at Hanoi, Vietnam, from 25 April 2001 to 31 December 2008. In this study back trajectories are used to identify long range transport into Hanoi for two of these sources, namely, windblown dust (Soil) from 12 major deserts in China and emissions from 33 coal fired power plants (Coal) in Vietnam and China. There were 28 days of extreme Soil events with concentrations greater than 6μgm-3 and 25 days of extreme Coal with concentrations greater than 30μgm-3 from a total of 748 sampling days during the study period. Through the use of back trajectories it was found that long range transport of soil from the Taklamakan and Gobi desert regions (more than 3000km to the north west) accounted for 76% of the extreme events for Soil. The three local Vietnamese power stations contributed to 15% of the extreme Coal events, while four Chinese power stations between 300km and 1700km to the north-east of Hanoi contributed 50% of the total extreme Coal events measured at the Hanoi sampling site. © 2010 Elsevier Ltd. Source


Tabbakh F.,Nuclear Science and Technology Research Institute, Iran | Khalafi H.,Institute of Nuclear Science and Technology
Nuclear Science and Techniques | Year: 2010

Accelerator-based target design and optimization is an approach for neutron generation. The target plays an important role for a neutron source on an electron accelerator. For optimizing a neutron source using 10 MeV electron beams of Rhodotron-TT200, Pb, Ta, or W alloys with Be were calculated as photo-neutron converter. The neutron yield, flux and energy were simulated using the MCNPX code. The results indicate that a 10 MeV electron beam is capable of producing high-intensity neutron flux of 1013n·cm-2·s-1 with average energy of 0.8 MeV. Source


Tafreshi M.A.,Institute of Nuclear Science and Technology
Journal of Fusion Energy | Year: 2014

In this paper, the theoretical ML model has been used to study the effect of three preliminary parameters (gas pressure, discharge voltage and the kind of the gas), to the current, azimuthal magnetic flux density, and the plasma layer pressure, in the Filippov type plasma focus device, Dena. Among others, it has been shown that to have an optimum pinch, the mentioned parameters should be selected in a manner so that the plasma sheath moves with an optimum velocity. A higher or lower velocity leads to pinch formation in an inappropriate time, when the plasma pressure is relatively low. © 2014 Springer Science+Business Media New York. Source

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