| The XRF analysis of light elements(this article refers specifically to elements with atomic numbers between 11 and 17)has an important guiding role in the control of many production processes.However,due to the characteristics of low X-ray energy and low excitation efficiency of light elements,the current EDXRF spectrometer is not ideal for the excitation-detection of light elements,and is greatly restricted in practical applications.This article focuses on the design and optimization of the front-end detection device for light element EDXRF analysis.Theoretical research and experimental analysis of the optimal geometry,layout and optimal working conditions of the X-ray tube in the detection device are carried out to improve the analysis of light elements by the EDXRF method.Effect.The main research results of the paper are as follows:(1)Combine the characteristics of light X-rays produced by light elements,select the excitation source,detector,secondary conversion target and vacuum environment used in the detection device,then design and install according to the geometric installation size of the selected model Connected mechanical parts,and designed and built an experimental detection device.(2)The MCNP5 simulation was used to compare the excitation detection effects of light elements in two measurement environments-vacuum environment and helium environment,and the "source-sample-probe" and "source-target-sample-probe" were analyzed.Angle and the optimal tube pressure for X-ray tubes when analyzing light elements.The results show that: the analysis of light elements is better in a vacuum environment than in a helium environment;when analyzing light elements,the optimal angle between "source-target" in the "source-sample-probe" model is 70°,The optimal angle between “sample-probe” is 80°;the optimal angle between “source-target” in the “source-target-sample-probe” model is 65°,between “target-sample” The best angle is 70°,the best angle between “sample-probe” is 60°;the best working voltage of X-ray tube is 10 k V.(3)T The angle and intensity distribution of the X-ray tube's outgoing rays are studied and analyzed experimentally.The experimental results show that the angle of the X-ray tube's outgoing rays is 16.8°,and the light intensity is evenly distributed.(4)Under the guidance of MC simulation results,an experimental study was carried out on the angle and distance of the geometric arrangement of the detection device,and the experimental results were consistent with the theoretical analysis.At the same time,the best tube pressure and tube flow parameters used in the measurement of light elements were tested.It was found that when the tube pressure was(9?10)k V and the tube flow was(1.5?2.5)?A,the characteristic peak-to-back ratio of the light element Optimal.(5)The instrument spectrum of the secondary conversion target was measured and analyzed,and the instrument spectrum after the conversion target was found to be cleaner and the background scattering was significantly reduced.Using two designed detection devices,the instrument spectra of several typical samples were measured and compared,and it was found that the secondary conversion target excitation method is better than the direct excitation method for exciting light elements.The two detection devices are designed to measure and analyze the S and “GSS” in coal samples,the Al and Si in geological samples and the Na and Mg in geological samples.The recommended value is more consistent. |
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