Standardisation of 238Pu using four methods of measurement

Four independent methods of measurement were used to standardise a 238Pu solution within the frame of an international key comparison organised by the Bureau International des Poids et Mesures, Sèvres: 4π liquid-scintillation spectrometry, alpha-particle counting at a defined solid angle, alpha spectrometry using a windowless 4π CsI(Tl)-sandwich spectrometer and a 4π pressurised proportional counter. The solid sources were prepared by quantitative drop deposition and a special source-drying technique. The weighted mean value of the activity concentration of 238Pu was found to be (360.2±1.0) kBq g−1 at the reference date (1 April 2001). The measurement methods, the results and the applied corrections are described and discussed.