title: Activity standardisation of 45Ca and 204Tl using the new TDCR system at CMI.
abstract: A new triple-to-double coincidence ratio (TDCR) system has been established at CMI as an additional technique for primary activity standardisation. Details of the detectors and the electronics are given. Construction of the optical chamber was validated using measurement of a (3)H standard-the efficiency achieved with Ultima Gold was 58%. Several methods of efficiency variation (coloured bands painted on vial, positioning and photomultipliers defocussing) are compared. Activity concentrations of (204)Tl and (45)Ca were determined with the TDCR method and with the efficiency tracer technique. Advantages of the TDCR method compared to the efficiency tracing method and agreement between results are shown.
authors.affiliation: Czech Metrology Institute, IIR, Radiová 1, 102 00 Praha 10, Czech Republic. jsochorova2@cmi.cz
authors.forename: Jana
authors.initials: J
authors.lastname: Sochorová
authors.forename: Pavel
authors.initials: P
authors.lastname: Auerbach
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Dutka
mesh_terms: D002132:Calcium Radioisotopes / Q000032:analysis* / Q000592:standards*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006207:Half-Life; D038622:Internationality; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards*; D012015:Reference Standards; D012016:Reference Values; D013794:Thallium Radioisotopes / Q000032:analysis* / Q000592:standards*
chemical_list: D002132:Calcium Radioisotopes; D013794:Thallium Radioisotopes