Research On Submarine In-situ X-ray Fluorescence Detection Device Based On MC

The purpose of this paper is to use theoretical analysis and MC numerical simulation to develop the research on the key technologies which are the excitation voltage of Mn,Fe,Cu,Zn and Pb elements,"source-sample-detector" geometric detection device,detection window and water effect.Improving the accuracy and sensitivity of multi element analysis in submarine in-stiu detection,it provides technical support for marine mineral resources exploration.The main achievements of the paper are as follows:(1)X-ray tube excitation voltage is optimized based on MC simulation.According to Mn,Fe,Cu,Zn and Pb 5 elements in the marine sediments,the peak to background ratio of Mn and Fe at 20 kV is more than 2/3 at the highest P/B.The peak to background ratio of Cu and Zn elements at 20 kV is higher.The peak to background ratio of Pb elements at 30 kV is the best.So,considering the higher peak to background ratio of element,we determine the work voltage of Mn,Fe,Cu,Zn is 20 kV and the work voltage of Pb is 30 kV.(2)Based on theoretical analysis and MC simulation,"source-sample-detector" geometric detection device is studied.According to normalized count and peak to background ratio,the best angle of "source-sample" is 10o,the best "sample-detector" is 20o and the best distance of "source-sample-detector" is 9mm.(3)The detection window effect is studied by using MC simulation technology.Considering safety,process design and the influence of the detection window thickness on the element characteristic X-ray count,the thickness of the detection window is determined to 1.5mm.The correction equation which is establised according to the influence of detection window on ray detection.The detection window of the thickness of the 1.5mm is corrected.The results show that the relative error of the detector window thickness after correction is less than 9% in comparison to non-detection window.The characteristic X-ray intensity of target element is simulated in the case of impurity and purity detection window.It is found that the interference of impurities to Mn,Cu and Pb elements is small but large in Fe and Zn.The correction equation is established based on the Fe and Zn characteristic X-ray strength relationship between impurity and purity detection window.When the content of Fe and Zn is 0.8%,the relative error of impurity after correction is less than 4% in comparison to impurityfree.The influence of water effect is studied by MC.The correction equation of water effect was established based on the scattered X-ray intensities of the primary X-ray as internal standard emited from submarine sediment samples and water.The results show that the relative error of the characteristic X-ray count after the water content correction is less than 10% in comparison to the X-ray count of target elements without water.When the thickness of the water layer of Mn and Fe is less than 1mm,the thickness of the Cu and Zn elements is less than 2mm,and the water layer thickness of the Pb element is less than 3mm,the relative error of characteristic X-ray count after water layer correction is less than 15% in comparison to none-water layer.