The presence of radon-222 in soil gas and ground water can indicate the existence of nearby uranium deposits even when heavy overburdens completely absorb the associated gamma radiation. Techniques to detect and measure radon have evolved during the past several years to the point where radon prospecting is routinely employed in a number of countries. A program to develop and field test a prototype system for measuring radon from soil gas and water is described. A prototype system employing a flow through scintillation detector was designed and constructed, utilizing standard commercial components, to provide a fieldworthy unit for testing the system concepts. Laboratory and preliminary field tests of this unit indicate that it can detect anomalous radon levels of less than 10 picoCuries per liter (pCi/l) in soil gas and ground water.

This dissertation, "Development of the Customized Radon Detector and Studies of the Radon Background Onsite for the Daya Bay Reactor Neutrino Experiment" by Kar-yee, Leung, 梁嘉怡, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: The goal of the Daya Bay Reactor Neutrino Experiment is to determine the last unknown neutrino mixing angle θ13, in sin22θ13 to sensitivity better than 0.01 at 90% confidential level in three years of running. In order to reach the goal, background from natural radiation should be controlled less than 50 Hz, accordingly radon, which is a naturally-occurring radioactive gas, is one of the factors need to be monitored. A High-sensitivity and High-reliability Hong Kong (H3) radon monitoring system is developed to support the slow control system of the experiment. It achieves the sensitivity requirement and fulfills the data acquisition specification by using an enlarged sample chamber, an improved electronic and a designed software, in addition to the dehumidifier system for long term use. Four final products of the radon detector were well calibrated and tested before application; the sensitivities of counted progenies Po-218 and Po-214 are 3.65 0.37 x10-2 cpm/Bq-m3 (C.F.is 27.42.7 Bq/m3/cpm) and 3.94 0.40 x10-2 cpm/Bq-m3 (C.F. is 25.42.5 Bq/m3/cpm). Its performance is the highest among the same type of commercial available products. This radon monitoring system has been successfully taking data as the background measurement of the experiment for more than half a year, and will continue to provide useful information for the following several years. From the results, the radon levels in the air in Experimental Halls and in the water of water systems were higher than expected, but still at the acceptable levels. Further works have to be done to control them at preferred levels. DOI: 10.5353/th_b5053415 Subjects: Radon measures

This dissertation, "Development of the Customized Radon Detector and Studies of the Radon Background Onsite for the Daya Bay Reactor Neutrino Experiment" by Kar-yee, Leung, 梁嘉怡, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: The goal of the Daya Bay Reactor Neutrino Experiment is to determine the last unknown neutrino mixing angle θ13, in sin22θ13 to sensitivity better than 0.01 at 90% confidential level in three years of running. In order to reach the goal, background from natural radiation should be controlled less than 50 Hz, accordingly radon, which is a naturally-occurring radioactive gas, is one of the factors need to be monitored. A High-sensitivity and High-reliability Hong Kong (H3) radon monitoring system is developed to support the slow control system of the experiment. It achieves the sensitivity requirement and fulfills the data acquisition specification by using an enlarged sample chamber, an improved electronic and a designed software, in addition to the dehumidifier system for long term use. Four final products of the radon detector were well calibrated and tested before application; the sensitivities of counted progenies Po-218 and Po-214 are 3.65 0.37 x10-2 cpm/Bq-m3 (C.F.is 27.42.7 Bq/m3/cpm) and 3.94 0.40 x10-2 cpm/Bq-m3 (C.F. is 25.42.5 Bq/m3/cpm). Its performance is the highest among the same type of commercial available products. This radon monitoring system has been successfully taking data as the background measurement of the experiment for more than half a year, and will continue to provide useful information for the following several years. From the results, the radon levels in the air in Experimental Halls and in the water of water systems were higher than expected, but still at the acceptable levels. Further works have to be done to control them at preferred levels. DOI: 10.5353/th_b5053415 Subjects: Radon measures