Analysis of the gamma time-intensity recorder trace located at How gave the best evidence of the rate of arrival of fallout. Use of the differentinl fallout collector and the time-intensity recorder for determining the period of fallout was restricted to the lagoon and islands of Bikini Atoll thereby limiting the distance to 15 nauticel miles. The average arrivel time within the area was 0 ¢ 28 nin with cessation averaging O + 117 min resulting in an average period of 89 min. These data compare well with that observed at I Uwher- the period was somewhat less than 2 hr. Residual fallout which war of such quantity thet it contributed little to the overall field was found to deposit for a period of soveral hours after the deposition of the main bedy of material. The Bikini £toll islands along the axis of the fallout pattern experienced fallcut over a longer period of time than did those islands lecated in a crosswise direction. 5.6.2 Shot No evidence was found of primary fallout at early times in the Bikini Legoon. Secondary fallout of maximum intensity of 40 mr/hr arrived at How Island 37.5 hr after Sh.s 2, as shown by the gamma timeintensity recorder. 5.6.3 Shot3 No differertial fallout collectors were operative for Shot 3. The gamma time-intensity recorder at How Island indicated a time of arrival of 0 + 38 min. Project 2.2 established an arrival time on Dog Island of aporoximately 0 ¢ 20 min.2/ 5.6.4 Shot 6 Eniwetok One differential fallout collector located at Alice Islam, Atoll, received significant fallout and indicated an arrival time of O + 35 min with the period of fallout being 65 min (Fig. C-18). 5.7 RATE OF ARRIVAL OF FALLOUT AND INTEGRATED DOSE Of the two gamma icnization time-intensity recorders installed on Yoke and How Islands of Bikini Atoll, only the one on How survived end recorded data from Shots 1, 2, and 3. These deta give accurate information cn rate of arrival of fallout “s well as time of arrival. 5.7.1 Rate of Arrival Table 5.7 presents the time of arrival of fallout end time of peak activity ‘or Shots 1, 2, and 3. The time at which the activity peak- is not the time of cessation of fallout. It is bert described as the time at which the rate of decay is greater than the rate of buildup of fallout. 70°