Dosimetry with optical fibres: results for pure silica, phosphorous and erbium doped samples

摘要

The potential for intrinsic dosimetry with three differnet fibre types through the gamma ray radiation indcued attenuation is investigated with respect to annealing, temperature dependencies, photo-bleaching and, to a limited extent, dose-rate. The radiation sensitivity of these three fibres covers an effective dose range of 0.1 Gy to 100 kGy which makes them suitable for a broad range of nuclear applications. With detailed analysis in both the pectral and temporal domain, it is shown that the long-term annealing effects can be suppressed by exploiting the stability of certain colour cnetres in the fibre core and adequate interrogation of the induced attenuation at a discrete set of wavelengths. Photo-bleaching is observed by employing a low power white light source (a few microwatts in the fibre0with Erbium doped fibres and when Germanium is added as a co-dopant with Phosphorous fibres. Temperature dependencies during irradiation and annealing are addressed from room temperature to 80 deg C. The Phosphorous and Erbium doped samples exhibit a reverse behaviour: the optical absorption increases with temperature.