FNTD radiation dosimetry system enhanced with dual-color wide-field imaging

• New method and optical imaging head was developed for FNTD used at high doses.
• Dual-color wide-field imaging used for color center concentration measurement.
• Green fluorescence corrected by diffuse reflection used for sensitivity correction.
• FNTD dose measurements performed in analog processing mode.

At high neutron and photon doses Fluorescent Nuclear Track Detectors (FNTDs) require operation in analog mode and the measurement results depend on individual crystal color center concentration (coloration). We describe a new method for radiation dosimetry using FNTDs, which includes non-destructive, automatic sensitivity calibration for each individual FNTD. In the method presented, confocal laser scanning fluorescent imaging of FNTDs is combined with dual-color wide field imaging of the FNTD. The calibration is achieved by measuring the color center concentration in the detector through fluorescence imaging and reducing the effect of diffuse reflection on the lapped surface of the FNTD by imaging with infra-red (IR) light. The dual-color imaging of FNTDs is shown to provide a good estimation of the detector sensitivity at high doses of photons and neutrons, where conventional track counting is impeded by track overlap.