Radioactive debris over Fairbanks, Alaska, on February 18, 1965

Abstract

A number of incidental detections of layers of intense radioactive debris have been reported as a result of balloon flights during the atmospheric nuclear weapon testing period 1958–1962 [Anderson, 1965]. Radioactive debris was observed in the lower atmosphere over Fairbanks, Alaska (65°N, 148°W), on February 18, 1965, in the course of a balloon flight to investigate bremsstrahlung X rays in the auroral zone. The balloon-borne detector, a Victoreen IB 85 Geiger counter shielded by 1/32 inch of lead with a narrow slit opening, recorded counting rates estimated to be over three times that from normal cosmic background radiations (see Figure 1). The debris appeared to lie in two or more layers. One layer, as indicated by the region of extremely high counting rate, extended vertically from 6 to 8 km in association with a layer of maximum wind speed. Such an association was reported previously by Mantis and Winckler [1960]. Above 8 km the counting rate is irregular but always higher than the normal rates measured on previous flights. Evidently the radioactive debris was inhomogeneously distributed in this turbulent region.