title: Application of thoron interference as a tool for simultaneous measurement of radon and thoron with a pulse ionisation chamber.
abstract: Pulse ionisation chamber (PIC)-based monitors measuring radioactive gas radon ((222)Rn) without energy discrimination will have interference due to thoron ((220)Rn) present in the atmosphere. A technique has been developed to use this property of interference for simultaneous measurement of radon and thoron gas. These monitors work on the principle of counting of gross alphas emitted from radon and its progeny. A theoretical model has been developed for the variation of thoron sensitivity with respect to the flow rate of gas through the monitor. The thoron sensitivity of the monitor is found to vary with the flow rate of gas through the monitor. Using this sensitivity, the sampling procedure has been developed and verified for simultaneous measurement of radon and thoron. The PIC-measured radon and thoron concentration using this procedure agrees well with those measured by using standard radon and thoron discriminating monitor.
authors.affiliation: Environmental Assessment Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.forename: R M
authors.initials: RM
authors.lastname: Tripathi
authors.forename: C G
authors.initials: CG
authors.lastname: Sumesh
authors.forename: A
authors.initials: A
authors.lastname: Vinod Kumar
authors.forename: V D
authors.initials: VD
authors.lastname: Puranik
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D008962:Models, Theoretical; D011834:Radiation Monitoring / Q000295:instrumentation*; D011886:Radon / Q000032:analysis*; D017687:Radon Daughters / Q000032:analysis*
chemical_list: D000396:Air Pollutants, Radioactive; D017687:Radon Daughters; D011886:Radon