AERMS Gamma Ray Survey

—A New Remote Sensing System by Helicopter—

Abstract

Since 1985, many detail data of natural gamma rays in air have been collected by AERMS (Asahi Environmental Radiological Measuring System) .These data are composed of the following gamma rays.
Channel Energy Window Nuclide
1 0.50-0.80 Mev Scattered gamma rays
2 1.30-1.60 Mev Potassium 40
3 1.60-2.00 Mev Bismuth 214 (Radon daughter)
4 2.40-2.80 Mev Thallium 208 (Toron daughter)
5 0.15-3.00 Mev Environmental Radiations
Measurements of gamma rays by this airborne system have been carried out in the regions with various geological conditions, such as fault, volcanic areas and hot springs zones, or landslide areas, fissure/fracture zones and ground water reservoirs. As a principal information in geological aspect, a phenomenon of difference between Radon and Toron has been obtained by computer processing of such data. There is significant difference in the falf-value period between Radon and Toron originated in rock, therefore Radon and Toron ascend to a ground surface through cracks and fissures in the upper layer of the crust, shows different ratios and count numbers of Radon radiation are, usually, larger owing to this longer half-value period of Radon.