Efficiency curve of the ionization chamber of the SIR

The efficiency of the SIR ionization chamber versus photon energy has been obtained by an iterative method, starting from a few monoenergetic γ-ray emitters. The relative standard uncertainty on the efficiency curve obtained is lower than 10−2 above 65 keV. An efficiency curve for β particles has been deduced in a similar manner, from measurements of (quasi-) pure β emitters. The possible uses of the efficiency curve to identify inconsistent SIR data or discrepant decay scheme data are discussed.