AERIAL PHOTO AND RADIOLOGICAL SURVEY PROGRAM 2. RADIOLOGICAL SURVEY The Aerial Radiation Surveys will be carried out by means of two Navy helicopters which’ will fly multiple missions from the USNS WHEELING station near the atoll or in the lagoons when possible. EG&G will supply the scientific flight crews and technical support personnel to operate and maintain the radiation measuring and position measuring equipment. The aerial radiation survey will employ an array of forty 12.7 cm diameter by 5 cm thick NaI(T1) scintillation detectors mounted within two pads which are hung externally on the helicopter. Signals from the detectors are fed into a multichannel data acquisition system mounted inside the helicopter. Gamma radiation data is accumulated continuously and recorded on magnetic tape once each second. In addition to the radiation data, position information provided by a microwave ranging system and a radar altimeter are also recorded on magnetic tape each second. Flight lines on each atoll island spaced 45 meters apart will be flown at an altitude cof 30 meters and a speed of 30 meters per second. A steering indicator, using signals from the microwave ranging system, will be used to aid the helicopter pilot in maintaining uniform flight line spacing. A large portion of the data reduction will be performed'in the field using two NOVA 840 minicomputer based data reduction systems. Radiation and position data are correlated on a second-by~second basis and processed in the form of radiation contours overlayed on aerial photographs. 5002691 I1I-9