4.7 CALCULATION OF DOSE RATE d FROM OBSERVED GAMMA FIELD-SAMPLE ACTIVITY RATIO Schuert (Reference 4) has calculated gamma fields for certain Operation Castle shots from a relation of the following kind: d =kI (4.7) Where: I = gammaactivity of collected fallout samples per unit area of collecting surface. k = factor calculated from gamma activity of fallout samples and gamma field intensities measured at or near the site of fallout collection. Both measurements refer to H + 4 days. When the activity is expressed® in units of mv cm™ 2 Schuert’s data give for the total collector: 0.048 <k =.0.48 : r hr! mv cm=2 and for the gumned paper collector: k = 0.36 22 -1 mv cm~2 Recently Miller (Reference 6) has calculated k using re-evaluation Rad-Safe gamma field data and values of gamma activity from fallout samples. From his data for Shot 1: k = 0.53 + 26 percent (standard error). For Shot 3: k = 0.34 + 21 percent. vs () (@) A value for k may be caleulated from Equation 4.4 as follows: = dr R I I =kI Where: k=dr= By substitution there results, using values based upon the spectral data for Shots 5 and 6: k = 0.35 ~1 rhrv" mv cm7? amma activity in mv 8 (gamma activity in mr hr-)) = acti 70