Two-Dimensional Coincidence Energy Spectrum Measurement And Data Processing

In order to determine the impact of natural radionuclides（such as uranium and thorium series）on humans,it is necessary to study their behavior in the environment in detail.Low radioactivity requires sensitive measurement technology;in addition,with the advancement and development of nuclear technology,nuclear accidents,nuclear tests,and nuclear facilities will release various artificial radionuclides during normal operation,and these nuclides will also Participate in the natural circulation of the atmosphere,oceans,etc.,spread to all parts of the world,and may seriously threaten the safety of human life through the food chain.However,artificial radionuclides have a very low concentration in the natural environment,so they also require very sensitive measurement techniques.The general measurement method is to measure the sample in the form of a single-parameter energy spectrum,and the two-dimensional（two-parameter）energy spectrum analysis technology that conforms to the method can obtain the conformable energy spectrum that cannot be obtained by the single-parameter measurement system,and only records the The count of cascade rays detected can effectively reduce the influence of other nuclides in the environment and improve the selection ability and sensitivity of the measurement system.With the advancement of nuclear science and technology and the development of electronic technology,the advantages of measurement systems that use software instead of electronic analog modules are gradually reflected.At present,the two-dimensional coincidence spectrum measurement system has problems such as poor portability,difficulty in real-time data transmission and processing,etc.Therefore,this paper studies a two-dimensional coincidence spectrum measurement method that is portable and universal for hardware devices,and based on this method Build a two-dimensional energy spectrum measurement system and verify its correctness through experimental measurements.A cascaded signal measurement device was built,and high-speed A/D conversion equipment was used to convert the analog signal into a digital signal;a data processing scheme was designed,and data processing software was developed using mixed programming techniques of LabVIEW and MATLAB.It consists of a data preprocessing VI（virtual instrument）module,a spectrum data acquisition and processing VI module,a coincidence event screening VI module and a two-dimensional compliance spectrum processing VI module.Combining the signal measuring device,A/D conversion equipment and data processing program,a two-dimensional digital coincidence energy spectrum analysis and measurement system was established.Measure the ⁶⁰Co source（101906.5Bq,2019.11）to verify that the numbers are in accordance with the algorithm,and the average measurement result is 101987.5Bq,and the relative error of the ten measurements is within 2%;the two-dimensional coincidence analysis method is used to measure the ⁶⁰Co（97597.6Bq,2020.3）source activity Degree,verify the two-dimensional energy spectrum measurement algorithm,the five measurement activities are within 2%,the average result of the measurement is 97547.7Bq,which is consistent with the results of the general compliance method;the measurement standard liquid radium source（4700Bq±3%,k=1）,select the cascade ray of energy 609keV and 1120keV as the measurement object,the coincidence count rate is 0.67s^-1,five consecutive measurements,the relative error of the measurement results are within5%;use two-dimensional coincidence energy spectrum analysis method to analyze And measuring liquid radium source,one-time measurement by one-dimensional coincidence energy spectrum projection,analysis of multiple gamma cascade rays,coincidence count rate increased to1.877s^-1,increased by 2.84 times,five consecutive measurements,the relative error of the measurement result is Within 5%.The measurement results prove the correctness of the data processing algorithm,and the two-dimensional coincidence energy spectrum measurement is realized,and the hardware of the two-dimensional coincidence energy spectrum analysis device realized by this method all uses common equipment and can be quickly transplanted.