fission and threshold detectors, were employed to document the neutron flux from devices, The fall-out instrumentation included a variety of types of collectors including samplers for total liquid and dry fall-out collection, intermittent collectors, and liquid aerosol collectors. The lagoon and island areas local to the shot zero points were heavily instrumented for all Operation Castle detonations except 74 encountered serious experimental and operational difficulties. The problem was attacked initially by the employment of an array of free floating buoys equipped with sample collectors. For @m area survey was mounted which involved surface and subsurfat ty measurements, water sampling, and hydrographic measurements, This survey covered a broad downwind zone to a distance of 200 miles and met with a large measure of success. Neutron flux me gemma data for and initial established the nature and magnitude of these effects for these types of high-yield surface detonations. Initial gamma radiation and neutrons are of minor significance in relation to other effects of such bursts, Considerable information was obtained on the distribution and characteristics of fall-out from high-yiel and water surface detonations. Extensive close-in data soric augmented by a post-shot survey of numerous downwind islands within the path of the fall-out toar 300 miles, The oceanographic and radiological survey £o> gD 20208 good coverage of the principle zone of downwind fall-out to a range of 200 miles. The results of the latter, ed good buoy samples taken 35 to 50 miles downwind for hould allow evaluation of the nature and dis- tribution of fall-out for high-yield surface-water bursts, WORT re These results indicate that surface bursts of megaton yields distribute casuaélty-producing fall-out over areas upwards of 1,000 Squere miles, The oceanographic survey vor ibs indicates that the tech- niques employed, coupled with a rapid synoptic monitor survey of the water surface by fast surface vessels or aircraft or both, provide a Péesible method for documentation of fall-out over water areas. ¢.3.3 Program 3, Structures The objective of Program 3 was to study the effects of blast in Copleaypo E LANL, J-Dly, 3T Loon seek é hi Documentation of fall-out over extensive downwind ocean areas