Preirradiation treatment influence on the radioluminescence of a nitrogen-doped optical fiber dosimeter

The dosimetry performances of a nitrogen-doped core (diameter of 8 µm) optical fiber, before and after 100 kV X-Ray preirradiation treatments, up to cumulated dose of 1 MGy (SiO${}_2$), to highlight their effects on the radiation-induced luminescence (RIL), are investigated. The RIL reproducibility versus dose rate calibration curves (in the 0.17-50 Gy s${}^{-1}$ range) are evaluated using four sets of ten different probes: three sets using preirradiated samples at 80 kGy, 280 kGy, 1 MGy, respectively, and one set with pristine samples. The RIL kinetics during ≈60 h long preirradiations at constant dose rate are also studied, showing a non-negligible bright burn effect. The main outcome is that the preirradiation improves the fiber dosimetry properties since it: 1) enhances fiber radiation detection sensitivity, 2) improves the linearity of the RIL dose rate dependence, and 3) suppresses the observed afterglow postirradiation effect. However, after preirradiation, larger dispersion between the different probes is noted, from 4% (non-irradiated samples) to 10% for the 1 MGy preirradiated samples. The possible physical explanations are discussed on the basis of the preirradiation filling deep traps that, competing with the RIL centers for the trapping of electrons released by ionization, influence the RIL efficiency. (© 2023 Wiley‐VCH GmbH)