Radiocarbon Dioxide detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

摘要

Monitoring of radiocarbon ($^{14}$C) in carbon dioxide is demonstrated usingmid-infrared spectroscopy and a quantum cascade laser. The measurement is basedon cavity ring-down spectroscopy, and a high sensitivity is achieved with asimple setup. The instrument was tested using a standardised sample containingelevated levels of radiocarbon. Radiocarbon dioxide could be detected fromsamples with an isotopic ratio $^{14}$C/C as low as 50 parts-per-trillion,corresponding to an activity of 5 kBq/m$^3$ in pure CO$_2$, or 2 Bq/m$^3$ inair after extraction of the CO$_2$ from an air sample. The instrument issimple, compact and robust, making it the ideal tool for on-site measurements.It is aimed for monitoring of radioactive gaseous emissions in nuclear powerenvironment, during the operation and decommissioning of nuclear power plants.Its high sensitivity also makes it the ideal tool for the detection of leaks inradioactive waste repositories.