High Sensitivity Method Research About Measurementing ²¹⁹Rn By Gas Flow Test

219Rn is a radioactive gas in nature. Due to the characteristics of its short half-life and its low content, it is not attract the attention of people like 222 Rn and 220 Rn. With the in-depth study of radioactive gas Radon, it get more and more attention of people in the application of isotope oceanography, highly enriched uranium stores and spent fuel pool. All these work need to be developed the 219 Rn standard source of 219 Rn and accurate measurement. Current sampling is one of the high efficient method of measuring 219 Rn.Gas flow test is one of the high efficient method of measuring 219 Rn. The detection sensitivity is the detector response to the change of the concentration or material. Measuring samples by using laboratory which is existing scintillation chamber, the scintillation chamber volume is 510 ml, the detection efficiency of scintillation chamber was 80%.The measurement results show that the volume of 510 ml of scintillation chamber when some of the current type measurement 219 Rn with the air volume flow detection, this situation is more serious when the flow rate is larger, The decay factor is small, reduced the detected particles and its daughter through this scintillation chamber, lower the sensitivity of the measurement. In addition, the use of medium-sized scintillation chamber volume is 1000 ml, appears in the flow rates under the same conditions.On the basis of research on 219 Rn measurement by using the existing 510 ml scintillation chamber and 1000 ml scintillation chamber.The paper designed a large volume of 2700 ml scintillation chamber, And some problems of the scintillation chamber has carried on the research and design, such as the direction of the gas flow, baffle configuration and zinc sulfide coating thickness and light collection efficiency, etc. Ensure high detection efficiency of the scintillation chamber, at the same time, large sample volume ensures the sensitivity of scintillation chamber.At the same time, through the liquid scintillate method have relatively long half-life of 219 Rn daughter 211 Pb, revised in time, found that the load ventilation method measuring 219 Rn daughter 211 Pb test result is 8.3Bq, for 83% of the theoretical value 10 Bq compared with made big scintillation chamber verification, the results accord with the good. we can get preliminary conclusion that the large scintillation chamber can measure 219 Rn source in a high sensitivity.