The Tritura Of ²²²Rn/²²⁰Rn Daughter Metrology Equipment Based On α Spectrum Method

The accurate measurement of 222Rn/220 Rn daughter does not only contribute to exactly measuring of the dose caused by 222Rn/220 Rn daughter, but also is an inevitable problem in excluding the disturbance of man-made radioaerosol.α spectrum could discriminate the energy of α particle radiated by different 222Rn/220 Rn daughter, so it improves the precision and shortens the time of measurement. In practical application, membrane filter sampling system and α Spectrum measuring system are parted and there are requirements of measuring operation, making expertise staffs in the laboratory operate the relevant instruments according to strict measuring process, which make it difficult to realize the accuracy, continuum, unattended operation required by man-made radioaerosol monitoring.Besides, the method of α spectrum measuring 222Rn/220 Rn daughter does not make the most of its advantage in unattended operation monitoring. This thesis, based on error analysis and contrast, redesigns electronic circuit by using the mechanical structures and detector of alpha760, coordinates with Raspberry Pi controlling computer and compiles software to develop a series 222Rn/220 Rn daughter measuring instrument based on α spectrum.Besides, I analyse the “tail” problems of α spectrum based on the data in the experiment.(1) Analyse the changing process of daughter numbers in and after 222Rn/220 Rn daughter sampling, and then deduce the solution formula and errors of three different measuring methods of α spectrum, contrast errors caused by measuring methods and list the recommended sampling time and measuring method.(2) Design circuit of nuclear electronics and mechanical structures control acquired by α spectrum data by utilizing the mechanical structure of the present alpha760 daughter measuring instrument.(3) Use Card Computer Raspberry Pi as the control center, compile the relevant software of control and data processing to acquire the information of time-energy spectrum, which make the maximum utilization of measuring data possible.(4) Discuss the problems of spectrum data disposal and α spectrum “tail” in the experiment, and give some feasible solutions.At present, the acquirement of α spectrum “time-energy” information of the instrument has matured, yet we need explore the best measuring time quantum and use the method of α spectrum to optimise the application of α spectrum data.