Contribution to the elaboration of large-area and high-efficiency β sources for the control of contamination detectors used in radiation protection

This engineering thesis reports works which aimed at taking a new ISO standard into account which concerned reference sources used for the control of contamination detectors, notably specifications related to the source and to the measurement. The author first presents the wished characteristics of β sources in order to comply with the standard. He reports the determination of a technique of fabrication of large-area sources (electro-spraying, centrifugation of a polymer in solution, drawing of a substrate with controlled rate), and discusses the choice of a polymer adapted to this fabrication technique. Then, he reports the study of the characteristics and properties of the polyvinyl alcohol (physical characteristics, macromolecular structure, solubility and plasticising, property of films of polyvinyl alcohol), the preparation of aqueous solutions of this alcohol, the incorporation of a radioisotope in the solution, and the study of characteristics related to the method of drawing a substrate immersed in a polymer solution. He reports the realisation of thin deposits by using the drawing method, and the control of the homogeneity of the β sources. Other possible realisations based on the drawing method are overviewed, and the limitations of this method are discussed