Equation(6)in Chin.Phys.090833(2000)is corrected.All subsequent derivations were given based on the correct Eq.(6),so the conclusions in the paper are not ffected by the rrata.
Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEO...Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEOS) using non-ionic alkylpolyethyleneoxide (AEO(9)) surfactant as templates. The results agreed with that of high-resolution TEM (HRTEM) measurement.展开更多
The small angle X-ray scattering of organically modified MSU-X silica prepared by co-condensation of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) show negative deviation from Debye’s theory due to the ...The small angle X-ray scattering of organically modified MSU-X silica prepared by co-condensation of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) show negative deviation from Debye’s theory due to the existence of the organic interface layer. By exerting correction of the scattering negative deviation, Debye relation may be recovered, and the average wall thickness of the material may be evaluated.展开更多
In the experiment to determine the plasma electron temperature, a modifiedmultichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energyMather-type plasma focus device energized by ...In the experiment to determine the plasma electron temperature, a modifiedmultichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energyMather-type plasma focus device energized by a 32μF, 15 kV (3.6kJ) single capacitor, with deuteriumas a filling gas. The ratio of the integrated bremsstrahlung emission transmitting through foils tothe total incident flux as a function of foil thickness at various temperatures is obtained forfoil absorbers of material. Using 3 μm, 6 μm, 9 μm,12 μm,15 μm and 18 μm thick aluminiumabsorbers, the transmitted X-ray flux is detected. By comparing the experimental and theoreticalcurves through a computer program, the plasma electron temperature is determined. Results show thatthe deuterium focus plasma electron temperature is about 800 eV.展开更多
Although quite a numer of papers can be found up to now dealing with the subject of the measurement ofwood density by using the X-ray exposure methods, direet scanning or radiographic photography, the following two as...Although quite a numer of papers can be found up to now dealing with the subject of the measurement ofwood density by using the X-ray exposure methods, direet scanning or radiographic photography, the following two aspects,which are very important from both theorctical and engineering application points of view, have not yet been properly handled. One is that the elementary analyses or the experimental measurement on the mass attenuation coefficients were notspecified in regard to spectnun energv distridutions [1]. In this connection, the ambiguities in the specification of the coeffiecients and in turn for thc results among studies arise when only one of the two parameters, namely wave length and applied voltage, of detining the energy spectrum of X-ray is given. The oher is that the relationships between the relative intensity and the sample thickness as well the wood moisture content [2], which are the critical factors for the design and theselection of X-ray apparatus, were not sufficiently examined. In addition, the knowledge of the measurelnent of woodmiosture content by using the direct X-ray scanning method is also almost unavaible now. In the study, the direct X-rayscanning method of measuring wood moisture content was at first investigated theoretically with respect to the relationshipbetween the mass attenuation coefficients of wood (beech, Fagus Sylvatica) and the maximum spectrum energy of X-ray.Secondly, the dependence of the relative intensity on the sample thickness and on the wood moisture content was analysed.The main advantage of the method is on-site nondestructive measuring of wood moisture content in the processes such asdrying, impregnation and unsteady mass diffusion. Specifically for the application in the area of biomechanics, the methodcan also bc used for understanding the water pathway within wood, for example, the water around the knots and the relation between the stress distribution and the local moisture content of wood.展开更多
In this paper we propose a new method for measuring the thickness of the GaN epilayer, by using the ratio of the integrated intensity of the GaN epilayer X-ray diffraction peaks to that of the sapphire substrate ones....In this paper we propose a new method for measuring the thickness of the GaN epilayer, by using the ratio of the integrated intensity of the GaN epilayer X-ray diffraction peaks to that of the sapphire substrate ones. This ratio shows a linear dependence on the GaN epilayer thickness up to 2 μm. The new method is more accurate and convenient than those of using the relationship between the integrated intensity of GaN epilayer diffraction peaks and the GaN thickness. Besides, it can eliminate the absorption effect of the GaN epilayer.展开更多
The variation in environmental scattering background is a major source of systematic errors in X- ray inspection and measurement systems. As the energy of these photons consisting of environmental scattering backgroun...The variation in environmental scattering background is a major source of systematic errors in X- ray inspection and measurement systems. As the energy of these photons consisting of environmental scattering background is much lower generally, the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence. A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison. Furthermore, it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.展开更多
文摘Equation(6)in Chin.Phys.090833(2000)is corrected.All subsequent derivations were given based on the correct Eq.(6),so the conclusions in the paper are not ffected by the rrata.
文摘Small Angle X-ray Scattering (SAXS) experiment using Synchrotron Radiation as X-ray source was used to determine the average wall thickness of mesoporous silica prepared by condensation of tetraethylorthosilicate (TEOS) using non-ionic alkylpolyethyleneoxide (AEO(9)) surfactant as templates. The results agreed with that of high-resolution TEM (HRTEM) measurement.
文摘The small angle X-ray scattering of organically modified MSU-X silica prepared by co-condensation of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) show negative deviation from Debye’s theory due to the existence of the organic interface layer. By exerting correction of the scattering negative deviation, Debye relation may be recovered, and the average wall thickness of the material may be evaluated.
基金This work was partially supported by Quaid-i-Azam University research Grant Pakistan Science Foundation Project Pakistan Atomic Energy Commission Project for Plasma Physics
文摘In the experiment to determine the plasma electron temperature, a modifiedmultichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energyMather-type plasma focus device energized by a 32μF, 15 kV (3.6kJ) single capacitor, with deuteriumas a filling gas. The ratio of the integrated bremsstrahlung emission transmitting through foils tothe total incident flux as a function of foil thickness at various temperatures is obtained forfoil absorbers of material. Using 3 μm, 6 μm, 9 μm,12 μm,15 μm and 18 μm thick aluminiumabsorbers, the transmitted X-ray flux is detected. By comparing the experimental and theoreticalcurves through a computer program, the plasma electron temperature is determined. Results show thatthe deuterium focus plasma electron temperature is about 800 eV.
文摘Although quite a numer of papers can be found up to now dealing with the subject of the measurement ofwood density by using the X-ray exposure methods, direet scanning or radiographic photography, the following two aspects,which are very important from both theorctical and engineering application points of view, have not yet been properly handled. One is that the elementary analyses or the experimental measurement on the mass attenuation coefficients were notspecified in regard to spectnun energv distridutions [1]. In this connection, the ambiguities in the specification of the coeffiecients and in turn for thc results among studies arise when only one of the two parameters, namely wave length and applied voltage, of detining the energy spectrum of X-ray is given. The oher is that the relationships between the relative intensity and the sample thickness as well the wood moisture content [2], which are the critical factors for the design and theselection of X-ray apparatus, were not sufficiently examined. In addition, the knowledge of the measurelnent of woodmiosture content by using the direct X-ray scanning method is also almost unavaible now. In the study, the direct X-rayscanning method of measuring wood moisture content was at first investigated theoretically with respect to the relationshipbetween the mass attenuation coefficients of wood (beech, Fagus Sylvatica) and the maximum spectrum energy of X-ray.Secondly, the dependence of the relative intensity on the sample thickness and on the wood moisture content was analysed.The main advantage of the method is on-site nondestructive measuring of wood moisture content in the processes such asdrying, impregnation and unsteady mass diffusion. Specifically for the application in the area of biomechanics, the methodcan also bc used for understanding the water pathway within wood, for example, the water around the knots and the relation between the stress distribution and the local moisture content of wood.
基金the National Natural Science Foundation of China(Grant No.69825107,NSFC-RGC Joint program:NSFC5001161953 and N_HKU028/00)
文摘In this paper we propose a new method for measuring the thickness of the GaN epilayer, by using the ratio of the integrated intensity of the GaN epilayer X-ray diffraction peaks to that of the sapphire substrate ones. This ratio shows a linear dependence on the GaN epilayer thickness up to 2 μm. The new method is more accurate and convenient than those of using the relationship between the integrated intensity of GaN epilayer diffraction peaks and the GaN thickness. Besides, it can eliminate the absorption effect of the GaN epilayer.
基金Supported by National Natural Science Foundation of China (10775082)
文摘The variation in environmental scattering background is a major source of systematic errors in X- ray inspection and measurement systems. As the energy of these photons consisting of environmental scattering background is much lower generally, the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence. A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison. Furthermore, it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.
文摘为了改善测厚系统抗干扰能力、降低系统复杂度、提高测量效率,研制了一种基于FPGA的电磁超声测厚仪。设计了基于FPGA的回波信号处理模块,实现了电磁超声回波信号的实时处理;采用SOPC技术,增强了软件灵活性,简化了系统硬件电路。实验结果表明:该测厚仪具有无需声耦合剂、抗干扰能力强、检测效率较高等特点,分辨力可达0.1 mm.
