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Key features of LEA products
The standards described in this catalogue are produced from base materials containing a minimum of radioactive impurities. Particular attention is paid to minimizing impurities throughout the production process.
Any impurities present in the finished products are identified and analyzed using alpha or gamma spectrometry or via mass spectrometry.
Impurity contents are stated on the calibration certificate as a percentage of the activity of the main radionuclide at the reference date. Where no impurities are detected, the detection limit is also stated.
“Uncertainty” represents an estimate of the possible variation between the level of activity certified by LEA and the actual activity. It is generally less than ± 5 %.
According to the standard NFX 07-001, the uncertainty of a measurement is defined as the closeness of agreement between the result of a measurement and the true value of the measurand (the measured variable, or the variable to be measured).
There are two types of uncertainty, depending on the evaluation method.
When calculating measuring uncertainty, all of the parameters Xi that impact the measuring result have to be identified, and their standard uncertainty quantified. Two methods can be used to assess the numerical value of the standard uncertainties associated with each of the uncertainty components :
Normal measuring conditions are as follows :
Standard solutions are characterized in terms of their specific activity (expressed in kBq.g-1), with the exception of multigamma ray standard solutions which are characterized in terms of their emission flux.
The stated activity applies to the main radionuclide, with the exception of decay products and identified impurities. The available nominal specific activities are defined for each radionuclide.
Other radionuclides and activity levels can be supplied on request.
In general, and unless specifically requested, the supplied activity may vary with respect to the nominal activity stated in the catalogue. The activity level and measuring uncertainty are stated in the calibration certificate provided with the source. This variation may be greater for short-lived radionuclides.