2. For each scurce energy, calculating a weichting factor (or relative dose) by multiclying the dose per photon in Step 1, above, by the number of source photons with that energy. , 3. For each source energy, estimating the fraction of dose due to source cnotons criginaily of that energy but cegraded by scattering wawmeians we to cncrgiss less olen than each of a set of arbitrarily chosen erergy values, +4 i, Computing the total dose due to all fhotons with energies up - to each chosen energy value by summing the een of Steps 2 and 39 ae above, for each of the criginal scurce energies, 8 The result ig an interral or cumlative airedose spectrum; ae5.3 a plot of photon energy versus the air-cose resulting from all photons3ary Noe from zero to that energy. From this, a rough differential dose histo-% at the™:e— _ gram is obtained by subtracting ordinates on the integral curve endpoints of each chosen energy interval, The use of graphical and mumerical methods makes the technique quite applicable to the de termina- tion of a number of such dose-enerpy distritutions. Figure 4,2 of heference 16 depicts the differential air-dose dise tribution for the Shct 1 H+ 9 hour data, in percent of dose per 0,05 Mey interval versus energy in Mev, Dose spectra based on the later data differed chiefly in the low energy region. The relative dose due to energy up to 100 kev averaged a bout hO percent as compared to 12 percent in the above cistribution, Three other dose distritutions were calculated from Shet 4 and later Shot i data and are shown in Figures 4.1, 4.2, and l.3. Figure 4.1, using the data of Tatle h.2, is an extreme case with respect to the low energy component, All other samples for all the shots lie tetween this and Figure 4.2 of Reference 16. Figures h.2 and h.3 give the dose distributions for the H + 4.1 and H + 5.2 day times on the other Shot 1 sample, Figure ,2 also indicates estimated error in portions below 0.3 Mev. The dose spectra are all seen to greup roughly into three regions with pesks at 100, 700, and 1500 kev, Since the spectra are those of bh to S day old fissicn ;reducts, at which time the Np¢39 activity is at its greatest relative value, the low energy proportion due to this muclide is higher than it was at H+ 2 days when the Np?¢39 canponent was still increasing (Figure 3.1). Based on this distritution, dosige and meter corrections for the low energy region during the exposure ried are therefore gencrous, During the several days before and after this tine the general spectrum shape apparently did not vary groasly in the higher enerzy regions, A total correction factor for . the survey instrunents was therefore calculated for each of these spec- tra and was assuned te hold for the period between fallout and surveys, as 4s described in Chapter 5, . . The process ecnsists essentially of the follcuwing steps: l. For each scurce energy, calculating the dose per photon contrituted by the unscattered portion of the radiation from each incre~ ment of source area, This requires an expression involving "true" and total absorption coefficients in air, cxpcnential intagral, source energy, and fracticn of dose cue to unscattered photens of that energy, hen . vals (Figures 4.1, b.2, and 4.3). came delivered to the surface of the exposed individual at a height of 3 feet above the plane by photons with energies in each of these inter-