Analysis Method Of Use HPGeγ-ray Spectromenty To Determin Uranium Radium Thorium And Potassium Activium In Geological Samples

In the many basic research about nuclear sciences and applications fields, nuclear spectroscopy analytical measurement technology plays an increasing role, HPGe spectrometer instrument is widely used in γ spectrum analysis of geological samples. γ ray spectrometry analys is by selecting the uranium and thorium decay series in a daughter nuclide(including potassium) appropriate to analyze the characteristic peaks of the parent nuclide activity concentration. For the gamma spectrometry analytical difficulties. Such as spectrum smoothing, peak region determination, background reduction and solution of radionuclide, these issues were studied and verified. The main conclusions are as follows.(1)The characteristic energy optimization: according to the principle of choicing γ-ray spectrum characteristic energy, the characteristic energy optimization is confirmed, Assessment of 238 U concentrations was based on measurements of the 92.6KeV.Assessment of 226 Ra concentrations was based on measurements of the 352 KeV and 609 KeV. Assessment of 232 Th concentrations was based on measurements of the 238KeV、583KeV、911Ke V.Assessment of 40 K concentrations was based on measurements of the 1460 KeV.(2)The spectral data smoothing: Different kinds of filtering methods(gravity model appoach /improved wavelet/ five points polynomial and least Square/ FFT ideal low-pass filtering) have different influence in spectrum peak count and the net impact area, while moving average filter based on five points polynomial and least Square is more suitable in view of processor speed.(3)Then use symmetrical peak search method zero area which have strong ability to detection the weak peak and distinguish overlapping peaks to determine the boundary of the channel.(4)Background reduction:using a modified full-spectrum base deduction of background subtraction method, and make research on the method of conversion width, The results show that using this method is simple and good(5)Method of determining the concentration of nuclides: using relatively of method, the results show that the radionuclide activity of 238 U concentration deviation is within 20%, the radionuclide activity of 226 Ra concentration deviation is within 16%, the radionuclide activity of 232 Th concentration deviation is within 12%,the radionuclide activity concentration of 40 K was larger than the actual. Base on the On this basis of the former, considering characteristic peaks affected by interference of other nuclides, Use efficiency calibration compared method formulas derivate out except interference nuclides after derivate in theory, The results obtained show that the latter method 238 U activity concentration deviation lower than the former, Less than 14%, The deviation of 40 K activity concentration reducing 14% than the former.Thesis and the results showed that: Select the characteristic energy and use efficiency calibration compared method to uranium radium and thorium and potassium quantitative analysis of geological samples is feasible.