• CO2
• CR-39
• dosimetry
• neutrons
• sensitization techniques
• UV

The growing need for accurate neutron dosimetry of the past decades, led to an increasing number of studies in this area, especially on CR-39, currently one of the main passive neutron personal dosimeters. Among the shortcomings to be addressed, counting automatically the smallest recoil proton tracks is a particularly difficult one. The present thesis was developed in this context, by studying two of the main sensitization techniques available in literature, the post-irradiation treatment with carbon dioxide under pressure, and the ultraviolet exposure treatment.
The work is divided in two main branches, the first is the study of the sensitization effects of the carbon dioxide treatment on CR-39 detectors exposed to fast neutrons and the second is the development of an original sensitization method combining carbon dioxide (CO2) and ultraviolet (UV) treatments.
For the carbon dioxide treatment, we did the first extensive investigation of its effects on CR 39 detectors irradiated to fast neutrons (most of the previous literature was based on alpha-particles). With these information we were able to optimize the treatment conditions, which improved the detector’s sensitivity, increased the average diameter of the tracks and reduced the treatment time, when compared to the routine protocol used commercially.
We also developed a novel sensitization method combining CO2 and UV treatments which, compared to the already optimized CO2 treatment, further increased the sensitivity of the detector and the average track diameter. The treatment time for this technique ended up being longer than the one of the optimized CO2 treatment, but shorter than the commercial protocol.