Development of High Dose Rate Sensing Method Based on Cavity Ring-Down Laser Spectroscopy

Abstract

We have developed a new method for high radiation dose rate monitoring based on cavity ring-down laser absorption spectroscopy and have measured 60Co gamma-ray induced chemical species in stationary and flowing air at the wavelength of 532 nm to check the basic performance of the new method. In the stationary air measurement, we confirmed linearity between the absorbed dose and the measured light absorbance by the radiation induced chemical species. Furthermore, in the flowing air measurement, we found the response time and the magnitude of the light absorbance largely depend on the air flow rate. In addition, a preliminary experiment was done to demonstrate the applicability to an intensity monitor for the intense undulator X-rays of BL47XU beamline at SPring-8. Results showed that the measured ring-down rate is proportional to the photon intensity and the detectable range is from 2×1011 to 3×1015 photons/s with time resolution around 3×102 s.