– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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SIR efficiency curve

The efficiency curve is commonly used to calculate the response of the ionization chamber for radionuclides not yet measured in the SIR. This is needed for two reasons:
  • to calculate the correction for impurities present in a submitted solution;
  • to give a point of comparison when a radionuclide is measured in the SIR for the first time.

The contribution to the ionization current of any high-energy beta-rays emitted is taken into account.

A mathematical solution to the efficiency curve has been completed in cooperation with the NPL, which enables impurities and strong beta-emitters to be evaluated with smaller uncertainties.

Efficiency curve of the SIR (iterative method):

Influence of impurities on 57Co SIR measurements:

International Reference System (SIR)
SIR efficiency curve
New mathematical solution to the efficiency curve
Extension of the SIR to beta-ray emitters
Participation in the SIR