ARMS II--LAS VEGAS AREA AERORADIOACTIVITY SURVEY

An Aerial Radiological Measuring Survey (ARMS) of the Las Vegas area was made for the Civil Effects Test Operations, Division of Biology and Medicine, U. S. Atomic Energy Commission, between May 21 and June 23, 1961. The survey was part of a nationwide program to measure present environmental levels of gamma radiation. Approximately 6000 traverse miles were flown, at an altitude of 500 ft above the ground, in a 100-mile square centered near Las Vegas. The EGG in only one sizable area are they above 800 counts/ sec. The south half of the area, which is much more radioactive, can be divided into three sections: (1) a west section, where the maximum count rate is usually below 800 counts/sec; (2) a center section, where the maximum count rate is less than 4000 counts/sec in half the section and less than 1200 counts/sec in the other half; and (3) a heterogeneous east section,more » where less than 1200 counts/ sec predominates but where there are sizable higher areas, The general distribution of radioactivity can be directly attributed to the geology of the area. Carbonate and clastic rocks usually are associated with low aeroradioactivity levels; metamorphic, intrusive, and volcanic rocks generally give rise to moderate to high aeroradioactivity levels. Although artificial radionuclides may have influenced the distribution of aeroradioactivity units in a few places in the extreme northwest portion of the area, the natural plus the artificial radioactivity in the northern area was much lower than the natural radioactivity of many units in the southern section. (auth)« less