Improvement of analysis results from the GAGG scintillator Compton camera operated on an unmanned helicopter by selecting stable flight conditions

Abstract

ABSTRACT A Compton camera system for use on an unmanned helicopter was previously developed to characterize the distribution of radioactive materials in highly contaminated areas. For this study, a Compton camera system was equipped with a small camera, laser distance meter, an attitude angle sensor, temperature sensors, and real-time monitoring software for better measurement of flight parameters and more precise detection of hot spot locations. To confirm whether the detection results were improved by the modifications, ground-level ambient dose equivalent rate distributions were derived from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan) and compared against readings from survey meters taken at the ground level. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude and restricting the deviation of the attitude angles. Between 6.0% and 7.6% improvement in the position resolution was achieved using the data from stable flight periods, even when only 1-minute data windows were used. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.