The Research on Matrix Effect and Correction Technology of Rock Sample in In-Situ Energy Dispersive X-Ray Fluorescence Analysis.

The mineral constituents of the rock sample can be analyzed with in-situ energy dispersive X-ray fluorescence analysis technology (In-situ EDXRF), the matrix effect of rock sample will effects on measurement results. The Monte Carlo simulation method is used to conduct fluorescence analysis spectrum with ideal measurement conditions, which provides analytical data for matrix effect research. The measured spectrum of seventeen kinds rock samples are being simulated, which has the same Cu content. Therefore, the influences with matrix effect of rock sample in in-situ EDXRF take Cu element for example. Based on correlation between Cu Kα X-ray intensity and spectral parameters, considering elements similarity of all kinds rock samples, it is found that the variation the Cu Kα X-ray intensity not only by the control of rock elements composition or rock classification. The matrix effect of rock samples must be classified according correlation between Cu Kα X-ray intensity and spectral parameters. After the matrix effect classification, fifteen kinds of rock samples, which belong to the same matrix effect, can be corrected more effective. Based on principal component analysis of similar matrix effect rock samples, it is found that the scattering background, target element K-series X-ray of X-ray tube and its incoherent scatter intensity can be a good description of Cu Kα X-ray intensity which is affected by rock matrix, thus it can be used to correct the Cu element measurement results. Certainly, this technology can also provide reference for matrix effect correction to other elements in rock.

The Study of the Rescale Method of the Spectrum Shifting in X-Ray Fluorescence Well Logging.

The X-ray fluorescence well logging technology is a significant method that can make quantitative analysis orsemi-quantitative analysis on the wellface. This method is very important to mineral exploration. The spectrum shifting is often observed in the X-rayfluorescence well logging because the temperature in the well changes acutely. The hardware is used to release the spectrum shifting and the software method is used to rescale the tiny spectrum shifting. There are too manyspectra to be rescaled in a well logging task by manually. In this paper, an auto method to rescale spectrum shifting, via the expert system model which is based on the special process to rescale spectrum shifting in manual, is presented. The symmetric zero-area conversion method, which is not sensitive to the changes of the baseline, is used to research the peaks. And then, the characteristic peaks will be identified by the standard errors, automatically. The prior knowledge (the last energy scale) and the gauss probability density function are used to analyze the peaks qualitatively and confirm the energy of characteristic peaks. Then the least square method is applied energy calibration. The singular deviation point, away from the calibrationline, will be rejected and the energy ratio will be obtained again. This method is applied for rescaling spectrum shifting in 322 spectra and obtains a satisfactory achievement.

[Influence of the Experiment Energy Dispersive X-Ray Fluorescence Measurement of Uranium by Different Excitation Source].

Aiming at the self-excitation effect on the interference of measurements which exist in the process of Energy dispersive X-ray fluorescence method for uranium measurement. To solve the problem of radioactive isotopes only used as excitation source in determination of uranium. Utilizing the micro X-ray tube to test Self-excitation effect to get a comparison of the results obtained by three different uranium ore samples--109 Cd, 241 Am and Mirco X-ray tube. The results showed that self-excitation effect produced the area measure of characteristic X-ray peak is less than 1% of active condition, also the interference of measurements can be negligible. Photoelectric effect cross-section excited by 109 Cd is higher, corresponding fluorescence yield is higher than excited by 241 Am as well due to characteristics X-ray energy of 109 Cd, 22.11 & 24.95 KeV adjacent to absorption edge energy of L(α), 21.75 KeV, based on the above, excitation efficiency by 109 Cd is higher than 241 Am; The fact that measurement error excited by 241 Am is significantly greater than by 109 Cd is mainly due to peak region overlap between L energy peaks of uranium and Scattering peak of 241 Am, 26.35 keV, These factors above caused the background of measured Spectrum higher; The error between the uranium content in ore samples which the X-ray tube as the excitation source and the chemical analysis results is within 10%. Conclusion: This paper come to the conclusion that the technical quality of uranium measurement used X-ray tube as excitation source is superior to that in radioactive source excitation mode.

[Analyzer Design of Atmospheric Particulate Matter's Concentration and Elemental Composition Based on ß and X-Ray's Analysis Techniques].

Monitoring atmospheric particulate matter requires real-time analysis, such as particulate matter's concentrations, their element types and contents. An analyzer which is based on ß and X rays analysis techniques is designed to meet those demands. Applying ß-ray attenuation law and energy dispersive X-ray fluorescence analysis principle, the paper introduces the analyzer's overall design scheme, structure, FPGA circuit hardware and software for the analyzer. And the analyzer can measure atmospheric particulate matters' concentration, elements and their contents by on-line analysis. Pure elemental particle standard samples were prepared by deposition, and those standard samples were used to set the calibration for the analyzer in this paper. The analyzer can monitor atmospheric particulate matters concentration, 30 kinds of elements and content, such as TSP, PM10 and PM2.5. Comparing the measurement results from the analyzer to Chengdu Environmental Protection Agency's monitoring results for monitoring particulate matters, a high consistency is obtained by the application in eastern suburbs of Chengdu. Meanwhile, the analyzer are highly sensitive in monitoring particulate matters which contained heavy metal elements (such as As, Hg, Cd, Cr, Pb and so on). The analyzer has lots of characteristics through technical performance testing, such as continuous measurement, low detection limit, quick analysis, easy to use and so on. In conclusion, the analyzer can meet the demands for analyzing atmospheric particulate matter's concentration, elements and their contents in urban environmental monitoring.

[The Study of Advanced Fundamental Parameter Method in EDXRFA].

The X-ray Fluorescence Analysis(XRFA) is an important and efficient method on the element anylsis and is used in geology, industry and environment protection. But XRFA has a backdraw that the determination limit and accuracy are effected by the matrix of the sample. Now the fundamental parameter is usually used to calculate the content of elements in XRFA, and it is an efficient method if the matrix and net area of characteristic X-ray peak are obtained. But this is invalide in in-stu XRFA. Also the method of net area and the "black material" of sample are the key point of the fundamental parameter method when the Energy Dispersive X-ray Fluorescence Analysis(EDXRFA) method is used in the low content sample. In this paper a advanced fundamental parameter method is discussed. The advanced fundamental parameter method includes the spectra analysis and the fundamental parameter method, which inserts the overlapping peaks separation method into the iteration process of the fundamental parameter method. The advanced method can resolve the net area and the quantitative analysis. The advanced method is used to analyse the standard sample. Compare to the content obtained from the coefficient method, the precision of Cu, Ni and Zn is better than coeffieciency method. The result shows that the advanced method could improve the precision of the EDXRFA, so the advanced method is better than the coefficient method.

[Analyse Output Specurum in Miniature Transmission X-Ray Tube of Aluminum Window and Silver Target by MC Simulation].

The miniature transmission X-ray tube is widely used in energy dispersive X-ray Fluorescence Analysis (EDXRFA). The miniature transmission X-ray tube with a small, low power consumption, X-ray emission efficiency that can be made the excitation source of handheld X-ray energy dispersive fluorescence analyzer. Beryllium (Be) is the most commonly used X-ray window material. But beryllium is expensive and toxic. At the same time set filtering window by aluminum (Al) to reducing low-energy scattering rays. This paper be adopted Al for exit window material of miniature transmission X-ray tube, achieve high-energy rays transmission and low-energy scattered radiation shielding, at the same time reduce production cost and difficulty. The present paper simulate the X-ray tube output spectrum of silver (Ag) target and aluminum window with different thickness by MCNP5. We consider the X-ray of low energy part is completely shielded when aluminum windows thickness is greater than 1.5 mm. We can conclude that 2 µm and 0.8 mm are the best combination of target thickness and aluminum windows through comparative analysis of existing research results. Then we can get flux of high energy part is big and low energy part is small when the target is 2 µm thick Ag and the window is 0.8 mm thick Al.