Transfer function for the activities calculations taking into account standards and samples matrix

The determination of the activities per unit mass of samples by gamma ray spectroscopy techniques relies on output curves obtained from standards, the matrix of which is generally water. The matrices of samples are often of different types. One is therefore justified in applying a corrective factor to apparent activity obtained in this way. Without correction, the greater the error, the weaker the peak energy used. After a brief review of a few topics, the authors of this paper will deal with the work carried out by GTN5 (standardisation working group consisting of specialists in this area). This work covered samples with various uniform matrices with interlad discs (sources). Subsequently, a collimator device was installed to determine the function between the linear absorption coefficient and gamma energy photon using a source of 152Eu and 241Am. Programmes were developed in part to determine this function from experimental points and in part to evaluate the number of gamma rays reaching the detector. A corrective factor C is then calculated. (authors). 6 figs., 4 tabs., 5 refs