Design Of ²²⁰Rn Measurement Device By Time Interval Analysis Based On STM32

The measurement of 220 Rn and its progeny have important significance in radiation protection, especially the low levels activity of220 Rn measurement, is still the difficulties of technology.In view of these problems above, the low activity 220 Rn device system measurement solutions based on STM32 interval analysis have been designed. This thesis presents the measuring 220 Rn principle of interval analysis method. According to the decay time relationship of220 Rn and 216 Po, the alpha pulse events can be extracted from the 220 Rn and other sources. The interval analysis method and MATLAB software has been used to analysis the nuclear pulse random sequence data of220 Rn and its daughter. The results verified this method can effectively measure low activity 220 Rn.The experiment device is constructed this thesis FD-125 scintillation chamber detector was used as the measurement device detector. The hardware digital control system was used STM32F103ZET6 microprocessor as the main control chip. The peripherals including touch screen, storage, temperature and humidity module. After finishing the PCB design, the components were beenwelding and debugging. Analog circuit mainly consists of two parts,firstly, using the preamplifier circuit to amplify the nuclear pulse signal from FD-125 detected; then adopt the main amplification circuit to achieve further enlarged. The signal converted into rectangular pulse waveform get through conversion circuit and finally connected to the STM32 microprocessor PG8 pin.The keil3 and emwin graphical interface design was used as the software parts, which were programmed by C language and used to realize the collection of nuclear pulse time series, storage, analysis and data upload, etc. The data processing part adopted interval analytical method to sum up the collected pulse interval distribution of time series and used half a linear least squares to fitting, eventually into the formula of 220 Rn activity calculation, the results were obtained and displayed.The measurement experiment research of standard 220 Rn source, the relative error under different flow rate is within 8%; The measurement hybrid field of standard 220 Rn, the relative error under different flow rate is within 9%. This study of development the measuring device of 220 Rn by time interval analysis have a certain foundation.