Monitering Radon Washout Events with Modified CosmicWatch Radiation Detectors*

Gamma-ray intensity variations were monitored for a number of precipitation events, including the remnants of two tropical cyclones, using a set of modified CosmicWatch radiation detectors. Clear signatures of radon washout/rainout were recorded for each event, with gamma-ray count rates in excess of 50% above normal in some cases. All of the washout/rainout events were correlated with measurements from an on-site precipitation monitor. The results demonstrate that low-cost CosmicWatch systems can be used for sensitive atmospheric radon monitoring.