Update of the BIPM comparison BIPM.RI(2)-K1.Cr-51 to include new activity measurements for the LNE-LNHB (France) and the pilot study result of the LNMRI (Brazil)

In 2006, two national metrology institutes (NMI) submitted samples of known activity of 51Cr solution to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM). Consequently, 28 samples have been submitted since 1977, from nine NMI and three other laboratories. The activities ranged from about 3 MBq to 90 MBq. The key comparison reference value (KCRV) has been updated and the degrees of equivalence between each equivalent activity measured in the SIR and the KCRV have been calculated. The results are given in the form of a matrix for eight laboratories to which the APMP.RI(II)-K2.Cr-51 results have been added. A graphical presentation is also given. (authors)