The fact that the mesn particle diameter at Ailinginse is smaller than et Rongelap cen be partially explained by enalysis of the wind profile which indicates, as one moves south from the axis of symmetry of the fellout pattern, that the particles delivered have smaller diameters (see Chapter 6). 5.2.2 Shot 6, ParticleSize The differentinl collector ststioned on Alice contained visible particulate as well as some liquic; the anelysis of particle size distribution 1s presented in Appendix GC. With a total of 321 particles measured the distribution was nearly log norm] with a geometric mean diameter of 1°80 b es shown in Fig. 5.8. from ground zero. 6.3 Alice was 3 nautical niles RATIO CF ACTIVE TO INSCTIVE PARTICLES One of the most difficult problems to resolve is the ratio of active to inactive fallout particles that arrive at a collecting instrument, This is especially true of the smaller diareter particles because it is extremely difficult to avoid pollution of the sample hy extraneous particulate. In this anelysis many small in»ctive particles were observed during the measurement of rarticle diameters. ‘Jn many cases these varti- cles were less than 5 b in dismeter, To arrive at a ratio, all pirti- culate was ignored that. did not have the characteristic white opaque color of fallout. Two samples were analyzed from Shot 1 fallout collected at lagoon stations where the effect of island dust pollution was minimized. The results are shorm in Fig. 5.9. Approximetely 25 per cent of the particles were found to be inective with the mean purticle size of the in- active particles smaller then the active, 5.4 PARTICLE DENSITY Particles from the Shot 1 lagcon station differential fallout collectors were analyzed to determine their apparent. density which is defined as the specific gravity of the narticle as a whole. Because of the station locations and the collectin;: instrument used, these particles hac a very high probability of being true fallout. Seventy-nine particles from stations 250.04, 250.17, and 250.°4 were measured. Density, averase Clameter, color, and relative activity were determined for each particle. Table 6.5 shovs the particle density found at each station. The overall averare density of the 79 particles was 2.36 e/cu cm with a standard deviation of 8.9 per cent. Attempts to find relationships between particle size and activity; particle size and density; and density and activity proved unsuccessful. All particle density data are tabulated in Appendix D,.