Gamma-ray Spectrum-dose Conversion Research And Computation Software Compilation Based On G(E) Function Method

When ?-ray spectrometers are used to measure radiation from other environmental pollutants such as the environment,soil,rocks,etc.,the radionuclide species is only distinguished.If the Gamma-ray spectrum can be converted to the corresponding air-absorbed dose rate,the two data can be obtained at the same time,this is an economical and efficient measurement method.The G(E)function method are used to perform Gamma-ray spectrum-dose conversion research in this study.Five standard radionuclide sources were used to calibrate HPGe Gamma-ray spectrometer with the energy range of 3 ke V to 10 Me V.The research combines with least-squares method and conjugate gradient to calculate the specific form of G(E)function and the calculation parameters of Ak.We compile a set of environmental gamma spectrometry dose conversion software based on the calculation method of the G(E)function and computer programming language.It has the functions of automatic reading ofGamma-ray spectrum files,data analysis and automatic dose calculation,so it achieves automatic calculation of Gamma-ray spectrum dose.In order to solve the specific form and calculation parameters of the G(E)function.There are five standard radionuclide sources(241Am?133Ba?60Co?137Cs?152Eu)which are selected for the calibration of the HPGe gamma spectrometer and according to the standard spectrums solve G(E)function of the spectrometer.Using the G(E)function calculate standard spectrum dose-rate,and the results compared with theoretical formula results.In order to verify the accuracy of the gamma-spectrum dose conversion of the G(E)function method,the experiment selects five dose rate points on the standard(137Cs)gamma radiation field at the Institute of Ionizing Radiation Measurement Institute,Chinese Academy of Metrology Science.The spectrometer performs spectrum measurement and using the G(E)function calculate the corresponding dose rate results of the spectrum.The results are compared with the standard results.In order to verify the accuracy of the calculation results of the environmental gamma spectrum dose conversion software.The experiment select four measurement sites in the field environment and measure environmental ?-ray spectrum.Using software calculate the environmental ?-spectrum dose,and using the high-pressure ionization chamber measure the corresponding dose-rate at the same location andaltitude.Finally,according to the software calculation results compared with ionization chamber measurement results.The research achievements include these points:(1)The specific form of the G(E)function is as follows:(?)In the above equation,K is the number of polynomial terms;Ak is the corresponding calculation parameter for the Kth term;Dr is the air absorbed dose rate,n Gy/h;T is the measurement time of the ? spectrum;i is the number of energy spectrum channels(i=1~n);N(Ei)is the count of the energy Ei's path.The results of using Ak parameters compared with the calculated results of the theoretical formula,the relative errors are1.9%?-2.9%?-1.7%?-2.5%?1.6%.The relative errors are smaller,and the calculated dose rate are more good,this result shows that the Ak parameters of G(E)function are right.(2)The research selects five standard dose rate points on the standard(137Cs)gamma radiation field of NIM and uses the HPGe Gamma spectrometer to measure Gamma-ray spectrum.The G(E)function is used to perform Gamma-ray spectrum-dose conversion calculation,and the calculation results preform dead time correction.The relative errors are 1.4%?-0.2%?0.2%?0.9%?-2.3%,which can expressthat the Ak parameters are solved correctly.If we want to reduce the error,we need to further optimize the dead time correction method.(3)The research selects four points on the NIM and uses HPGe Gamma spectrometer to measure the environmental Gamma-ray spectrum.Using the environmental Gamma-ray spectrum dose conversion software calculates the corresponding results of the environmental Gamma-ray spectrum.After the results aid the cosmic ray dose rate(+34.7 n Gy·h-1),The relative errors are 0.8%?2.7%?-0.9%?1.8%.So the results express that the software operation is effective and the calculation results are reliable.