SMALL BOY SHOT FALLOUT RESEARCH PROGRAM Ky = 2 £,Ko, J 53 (10) where f, is the fraction of the total activity carried by particles with a range in diameter designated by j and Ky), is the value of K) for the Same particle-size groups. However, for a determination of the variation of Ky) with particle size, the variation of r,, andr; with particle size must be known, and approximate values of q or Dq must be determined. The average value of ley (and of r,) for the intensity summation can be calculated in the same way as K, so that r= ~ fy, (11) where r, is the Tey value for the j¢z particle group. TREATMENT OF THE DATA Preliminary analyses and correlations of the radiochemical data and gross-sample-activity, sieved-sample-activity, decay-rate, and intensity measurements in the field on the fallout from the Small Boy shot have been made, leading to the evaluation of preceding parameters. Certain simplifying assumptions are made for portions of the analyses to facilitate the treatment of the data and the presentation of the computational results, First, it is assumed that, in Eq. 3, the values of r,k, are small compared with the values of Lips and K, is represented only by Ky = Dar,k,. (12) The values of Ky) were determined according to Eq. 2, in which the I, value of each fallout-collecting station was derived from correlations between data from gammaintensity time recorders (GITR’s) and activity measurements on the collected samples: The values of A; were derived from radiochemical analyses of the collected fallout samples, and the fission yield equivalent for each sample was based on the amount of zr found in each sample.’ The values of ry, were determined by taking the ratio of the ion current per fission of a gross fallout sample, as measured in a calibrated 47 ion chamber’ to the computed ion current per fission for an unfractionated fission-product mixture.’ In the field project,’ the radioactive content of all collected gross samples and all sieved