Evaluation of some parameters which influence the ESR measurements for thefading study of alanine dosimeters

Since several years, with the evolution of ESR spectrometers, the measureme nt of low absorbed doses seems to be accessible by alanine dosimetry. Some laboratories have realized important progress in this domain, but the influ ence of external physical and chemical factors that modify the results (fad ing) is not well quantified for using them with a sufficient accuracy for n ational or international comparisons, typically less than 3%. The first exp erimental study of combined effects has been realized in our laboratory. A necessary multiparametric approach (experimental design) has shown the comp lexity of the problem to serve before creating a physico-chemical model of the observed phenomena. The chosen methodology permits us to give the first quantitative approach of the fading for applied metrology.