Delayed Coincidence Method Of Radon Isotopes To Distinguish Between The Experimental Apparatus

In recent years,the detection technology of Radon and its daughters have been developing rapidly at home and abroad .Among these method , methods for detemination of 222Rn and 220Rn are more and more mature. In contrast, it is difficult to measure 219Rn.Recently, studies of marine coastal waters are very popular. The development trend of sea offshore research in our country is use Ra and its isotope to trace coast of ground water on estuarine and nearshore coastal water quality. It can use delayed coincidence method measure 220Rn and 219Rn to indirectly discriminate 224Ra and 223Ra.Further.measurement of Rn and its isotope base on the delay-coincidence method can also provide reference to the measurement of low concentration Rn in the air.The thesis elaborates research purpose and significance of the exprimental facility of radon isotope discrimination system based on delayed-coincidence measurement. Then the working principle and process of delayed coincidence method is analyzed and discussed. Microcontroller is used as data processing core to control the delayed coincidence pulse counting circuit(Precision timers LM322 are used for delay-coincidence to Rn isotope), which consisted of pulse amplifier, signal shaping circuit, delayed coincidence circuit,counting circuit. Further more, the main purpose of the exprimental facility is to distinguish 219Rn and 220Rn. Therefore, it can be used for coincidence pulses counting, data pocessing,liquid crystal display, it also provides the keyboard interface and serial commumication with pc function,etc.The simulation experiment and Comparative experiment are performed using the signal generator.