Aeroradiometric measurements in the framework of the Swiss Exercise ARM22

The flights of the civil (ARM22c) and military (ARM22m) parts of the exercise were performed between June 13th and 17th and between September 5th and September 9th, respectively. Both parts of the exercise included the measurement of altitude profiles. Two profiles were measured during ARM22c over Lake Thun and one profile during ARM22m over Lake Neuchâtel with sufficient altitude range to determine the slope of the altitude-dependent cosmic correction. The altitude profile over Lake Neuchâtel showed a clear deviation from the expected profile, suggesting a massive influence of airborne radon progeny on the result. According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Beznau (KKB) and Leibstadt (KKL), the Paul Scherrer Institute (PSI) and the intermediate storage facility (ZWILAG) were surveyed with an extension of the measuring area into German territory, following a request of German authorities. The site of the former Lucens reactor was measured and found unobtrusive in the measured data. Background flights were performed over several Swiss cities, regions and valleys. Besides attenuation effects of water bodies, variations of natural radionuclide content could be observed. Remains of the Chernobyl deposition were detected near the French border and in southern Switzerland.