Novel dose rate monitoring for intense radiation fields based on cavity ring-down laser spectroscopy

For dose rate monitoring in high level radiation fields, we have proposed a concept of novel dose rate monitoring method based on high sensitive laser absorption spectroscopy technique for radiation induced chemical species. The yield of the species depends on the intensity of the radiation field. The dose rate of the radiation field, therefore, can be derived from concentrations of the species. We have adopted cavity ring-down spectroscopy, which is an ultra high sensitive laser absorption spectroscopy, to measure trace quantities of radiation induced chemical species. We have tried proof-of-principle experiments through the off-line/on-line measurement of ⁶⁰Co gamma-ray induced NO₂ in the air. From these results, it has been verified that the present cavity ring-down measurement is quite useful as a dose rate monitoring method for intense radiation fields with high radiation resistance, where the expected performance will be the detectable range of the absorbed dose rate is from 0.5 to 2 × 10³ Gy(air)/s with the time resolution of about 30 s.