Study On The Reference Radiation Field And Quantity Transfer Of Medium Energy X-ray

With X-rays being widely used in industrial flaw detection,material analysis,disease treatment,medical diagnosis,scientific research and other important fields,people's lives have been closely related to X-rays.According to statistics,the contribution of nuclear technology in the gross national product(GDP)of the United States and Japan accounts for about 3%-4%,and the annual output value of nuclear technology in the United States is about 600 billion US dollars.China's nuclear technology produces an annual output value of about 14 billion US dollars,accounting for only 0.3% of the country's gross national product(GDP).China's nuclear technology application has a large market and good development prospects.At the same time,China has paid more and more attention to the environmental problems brought about by nuclear radiation,and established environmental level X-ray radiation quality,and made research on the measurement of dose equivalent around the environment.This paper relies on the national key research and development plan "Research on key technologies of low-dose rate X-ray and ?-ray measurement",and establishes five extremely low 55,70,100,170,240 kV in the X-ray reference radiation field of China Institute of Metrology.At the dose environment level,the kerma of 55,70,100 kV radiation air reached about 500 nGy/h,and 170,240 kV reached 5uGy/h,and the thickness of each radiation absorption sheet was determined.The radiation field was measured at a distance of 100 cm and 300 cm from the focus of the optical machine using a finger-type ionization chamber.The result showed that the diameter of the radiation field was better than 95% at 1 cm in 100 cm,and the diameter of the radiation field was better than 95% at 300 cm.The diameter of the effective radiation field at 4m is about 48 cm,which meets the experimental requirements.The average energy of different radiation qualities is obtained by using the high-purity germanium detector to measure the energy spectrum,the average energy of different radiation qualities is: 55 kV,70kV,100 kV,170kV,240 kV,and the average energy is: 50.15 keV,63.63 keV,86.85 keV,155.11 keV,and 214.53 keV.When the average energy is equivalent to the effective energy,it can be calculated that the half-value layer is between 0.31 and 5.09 mm Cu.The Monte Carlo simulation software was used to simulate each radiation mass spectrum and compare it with the measured spectrum to meet the experimental requirements.The work of magnitude transfer was carried out,and the high pressure ionization chamber,FHT 192 ionization chamber and 6150 AD dosimeter were respectively scaled.The calibration curve of the calibration was consistent with the instrument's factory response curve,and the accuracy of the calibration was verified.According to the A and B assessment methods,the uncertainty of air kerma kinetic energy measurement and calibration factor was evaluated by combining temperature,pressure,repeatability and other factors.The uncertainty of air kerma energy measurement was 1.642%.The uncertainty of calibration factor is 2.923%.