Study and characterization of the response functions of solid state nuclear track detector: application to radon and neutron dosimetry

This thesis was prepared in co-tutelage between the University of Strasbourg and the University of Technical Sciences and Technology of Bamako (Mali). It deals principally with the characterization of Solid State Nuclear Track Detectors (SSNTD) for measuring radon and neutrons in conformity with the new recommendations of the International Commission for Radiation Protection (CIPR-103). The response functions of PN3 and Neutrak, associated with adapted converters, have been studied in irradiations with neutrons at the Am-Be irradiator of the IPHC (Institut Pluridisciplinaire Hubert Curien), with 1 to 3 MeV protons of the Van de Graaff accelerator of the INESS (Institut d'Electronique du Solide et des Systemes) and by reference thermal and fast neutrons at the IRSN (Institut de Radiologie et de Surete Nucleaire). As concerns neutron dosimetry, we could reproduce the results of fast neutron intercomparison test organized by the IRSN, which validated our experimental methods and permits them to be applied to thermal neutrons. A prototype neutron dosimeter based on thermal detection has been successfully tested at the IPHC's irradiator. The feasibility of a dosimeter to discriminate thermal and fast neutrons using boron-containing BE10 and BN1 converters has been demonstrated. Calibrations of PN3 with protons and alpha particles will permit reconstituting neutron energy spectrum and to determine the associated dose. Calibration of CR-39 in a ²²²Rn chamber furnished the value 0.12 ± 0.02 tr.cm^-2.d^-1.Bq^-1.m³ that can be compared to the value 0.13 tr.cm^-2.d^-1.Bq^-1.m³ obtained by MCNPX simulation. As an application, the concentration and annual effective dose of radon has been determined for the first time in some dwellings of Bamako. All of the values are within the security limits recommended by the CIPR. Also for the first time, measurements by gamma spectrometry and by contact radiography were made on samples of Malian soil. The mass activities measured for the regions of Segou, Sikasso, Bamako and Kayes fall in the range of 19.9 to 132 Bq.kg^-1. (author)