最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Both X- ray diffraction and Rutherford backscattering spectrometry- channeling have been used to analyse the damage of the dual ion （Pt and S） implanted yttria stabilized zirconia ,before, and after thermal annealing. The RBS- C results show high self-annealing effect . during implantation at room temperature, and the XRD measurements indicate that sulfur can affect strongly the orientation of Pt crystallines formed during thermal annealing. ,关键词：lon implantation;YSZ single crystalline;Lattice damage;Rutherford . backscattering spectrometry- channeling;X- ray diffraction
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发布时间：2021-04-09 - 摘要：Nanocrystalline SnO2 and SiO2- doped SnO2 samples prepared by the Sol- gel process have been investigated by X- ray diffraction and positron lifetime spectroscopy. lt was shown that only two kinds of defects were found in the interfaces of both samples, i.e.free volumes and microvoids. lt appeared that when the sintering temperature was lower than the crystallization temperature, the grains grew slowly, and above this temperature the growth became faster. Furthermore, grain growth of the pressurized samples was slower than that of the powder. And SiO2 doping effectively restrained the growth of nanocrystalline SnO2 grains,关键词：Positron lifetime parameters;X-ray diffraction;Nanocrystalline SnO2 thus improving thermal stability of the materials .
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发布时间：2021-04-09 - 摘要：The structure and control method of the plasma horizontal position equilibrium control system in the HT-6M Tokamak have been analyzed theoretically. A high power GTO chopper and the Bang- Bang control method are used and a good result is Obtained.关键词：Nuclear fusion;Plasma;Equilibrium control
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发布时间：2021-04-09 - 摘要：The effects of various parameters on measuring TNT densities in cannonprojectile casing were discussed . The density measurement was performed by using the concept of equivalent , physical absorption thickness, the technological process of floooding water into projectile casing, and the nondestructive inspecting formula deduced on gamma- ray transmission and flooding method .关键词：Gamma nondestructive inspection;TNT density;Equivalent physical absorption thickness
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发布时间：2021-04-09 - 摘要：简要介绍冲击磁铁在加速器中的应用以及微秒脉冲磁场的测量原理，并对整个测量系统的误差加以分析说明。关键词：冲击磁铁;微秒脉冲磁场;凸轨;峰值保持;光电隔离
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发布时间：2021-04-09 - 摘要：The SFEL high brightness injector consists of a ns- grid gun driven at 476MHz, a 476MHz subharmonic buncher and a 2856MHz travellingt wave buncher（TWB） with high field gradient. Electron beam leaving the injector is then injected into a constant gradient travelling-wave accelerating section（Accl, SLAC type）. By using programs ETP, PARMELA, PLS- IM-60 etc., beam dynamics simulation was performed from the gun to. the end of Accl in order to find the optimized gun electrode geometry, sutbharmonic buncher gap voltage, bunching drift distance, TWB injecting phase, TWB structure parameters and axial magnetic field profile for predicting beam quality requested.关键词：Injectcr;Beam dynamics;Buncher
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发布时间：2021-04-09 - 摘要：Seven elements, i.e. Br, Ca, CI, Cu, I, Man and Na, in gallstones from 22 patients have been determined by neutron activation analysis. It is found that the concentrations of Br, Cu and Mn in " black coal cinder" - like gallstones are significantly higher than those in cholesterol and pigment gallstones by factors of 5.5- 6.9, 26- 119 and 23- 76, respectively. The concentrations of iodine in some gallstones are higher than those in normal human fluid and even higher than those in thyroid in a few cases, which suggests that iodine play a role in the formation of gallstones.关键词：Gallstone;Minor and trace elements;Neutron activation analysis
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发布时间：2021-04-09 - 摘要：In order to measure the concentrations of 222Rn and 220Rn in indoor air, the slightly refitted 10cm charcoal canister has been used for active sampling. After sampling, the charcoal canister has been measured by using a gamma- ray spectrometer and a HPGe detector. After calibration, concentrations of 222Rn and 220Rn have been obtained according to two characteristic Y peaks at 352 and 239keV. For 222Rn and 220Rn calibration factors were 0.263 and 0. 182m3Bq-1min.-1, respectively, The above validation method has been tested by measuring 222Rn and 220Rn concentrations in one general laboratory and one dwelling under different conditions. The 222Rn concentration has been found to be 45.5 - 140Bq. m-3 and the 220Rn concentration to be 4.92-14.2Bq . m-3关键词：Charcoal canister;Active sampling;HPGe y spectrometer;222Rn;220Rn
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发布时间：2021-04-09 - 摘要：Dose equivalent rates for X rays in mazes of 7 medical electron accelerator facilities producing X rays of 6, 8 or 18 MV were measured using the 2570/1A FARMER dosimeter and FJ- 347A X-Y dosimeter, which were calibrated at National Bureau of Standards. The measurement results indicate that X ray dose equivalent rate reaches maximum at the inner entrance of the maze and the ratio of the dose equivalent rate to the absorbed dose rate from the useful beam at the isocenter is more than 5.5 × 10-5 as the distance from the inner entrance to the isocenter is less than 5.2m. The dose equivalent rates decrease gradually with increasing distance. The dose equivalent rates in tunnel of the maze are less than 10-6 of the absorbed dose rate from the useful beam at the isocenter. The variation of dose equivalent rates in mazes with cross-sectional areas and path lengths of the mazes follows an exponential attenuation law. The dose equivalent rates in these mazes were also evaluated using a model given in this paper, and compared with the measurements.关键词：Maze;Medical electron accelerator;X ray dose equivalent rate
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发布时间：2021-04-09 -
- 摘要：Abstract关键词：微通道板;探测器;探测效率;丰度灵敏度
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发布时间：2021-04-09 - 摘要：In this paper, the direct demodulation method used in astrophysics is applied to the imaging recoanstruction in nuclear medicine. One slice Monte Carlo sample was studied, and the result showed that the method has a very high sensitivity and spatial resolution for small- size sources, Compared with other traditioanal methods it has some advantages and may be used in nuclear medicine to carry out early detection of small Cancer tissues.关键词：Direct demodulation;Imaging reconstruction;Non-linear constrain
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发布时间：2021-04-09 - 摘要：Variations of positron lifetime parameters with strain for the high purity iron samples with three ways of deformation （compression, cold- rolling and tension） have been investigated. Experimental results showed that when only one way of deformation （e. g. tension） was considered, our results were in accordance with the previous references, lt was found that variations of the mean lifetime with strain （i.e. the （ . ） curve） depended on the way of deformation. The . （ c ） curve for compression was, evidently higher than that for tension, and the . （ . ） curve for cold- rolling was ,between them. lt seems that the difference in . （ . ） curves . for various depends .on the types and concentrations of defects.关键词：Positron annihilation;lron;Deformation
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发布时间：2021-04-09
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