title: Primary activity measurements with a 4πβ-4πγ coincidence counting system.
abstract: The radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba solutions have been standardised using a 4πβ-4πγ coincidence counting system we have recently set up. The detection in the beta channel is performed using various geometries of a UPS-89 plastic scintillator optically coupled to a selected low-noise 1in. diameter photomultiplier tube. The light-tight thin capsule that encloses this beta detector is housed within the well of a 5in.×5in. NaI(Tl) monocrystal detector. The beta detection efficiency can be varied either by optical filtering or electronic discrimination when the electrons loose all their energy in the plastic scintillator. This 4πβ-4πγ coincidence system improves on our 4πβ(PC)-γ system in that its sample preparation is less labour intensive, it yields larger beta- and gamma-counting efficiencies thus enabling the standardisation of low activity sources with good statistics in reasonable time, and it makes standardising short-lived radionuclides easier. The resulting radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba are found to agree with those measured with other primary measurement methods thus validating our 4πβ-4πγ coincidence counting system.
authors.affiliation: Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland. youcef.nedjadi@chuv.ch
authors.forename: Youcef
authors.initials: Y
authors.lastname: Nedjadi
authors.forename: Claude J
authors.initials: CJ
authors.lastname: Bailat
authors.forename: François O
authors.initials: FO
authors.lastname: Bochud
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D011868:Radioisotopes / Q000032:analysis*; D011874:Radiometry / Q000295:instrumentation*; D012588:Scintillation Counting / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D014159:Transducers
chemical_list: D011868:Radioisotopes