Résumé:
The thesis proceeded in the context of gamma spectrometry analysis; it is divided into two major parts: The first part is devoted to the simulation of the detector used in the experiment to study some parameters, which we could establish a relationship between the detection efficiency, linear attenuation and selfabsorption of the sample with the radiation energy and the density of the material. The second part is devoted to the experimental measurement of the environmental radioactivity in eight samples of different natures (soil, Phosphates ores, iron ore, rocks of a mountain), which was marked with the normal concentrations of natural radionuclides in six samples (soil, rocks). In the two samples of phosphates ores, it was found significant concentrations of natural radionuclides, in which the calculated of hazard indexes have been higher than the thresholds. We have also marked, in these two phosphate ores, effective dose rates higher than those recommended by UNSCEAR (HE=0.3 mSv/y).
