title: The development of a 222Rn standard solution dispenser at NPL.
abstract: The design, operation and performance of a unit for dispensing standardised aqueous solutions of 222Rn is described. The unit consists of a sealed polyethylene capsule (containing a known weight of a 226Ra standard solution) immersed in water inside a cylindrical stainless-steel accumulation chamber. The chamber is fitted with valves at each end and has a central bellows so that the chamber can be compressed to dispense solution. The degree of compression, and thus the weight of solution dispensed, is controlled by a microprocessor-controlled motor-drive mechanism. The solution is dispensed via a needle positioned beneath the lower valve.
authors.affiliation: National Physical Laboratory, Queens Road, Teddington, Middlesex, TW11 0LW, UK. julian.dean@npl.co.uk
authors.forename: J C J
authors.initials: JC
authors.lastname: Dean
authors.forename: P
authors.initials: P
authors.lastname: Kolkowski