lial | . 1,05 x lo-? D sr90 - “As. 80 Where D i=l e (+ 6.8 x 107)(ts = tni) n = » 1 = " sr9 Ini lL, — NL e = A (tg - ty) (t, - tay )t-4 me/mi* of sr90 3.5 x 107° for I ni 5000 (Tropospheric) 4.7 x 1074 for Int 5000 (Stratospheric) -6 pose = Ay ROIS iel ¥ : a Gg -X(t, ” tni) Dose = Infinity y dose in millirads Defects of System There are a number of defects in the overall gummed film system and in fact, it only deserves the effort expended because there were no other types of sampling available for the time and locations at which most of these measurements were made, These defects will be discussed individually even though it is not possible to give good numerical estimates of the errors involved, The measurement is a total beta count only and is subject to the errors of self-absorption and the change in average energy of mixed fission products with time. The self-absorption is partially corrected for by using basic standards with the same weight of material as found in the average fallout sample. No correction is made for such heavy or light samples as may appear The average energy of the mixed fission prod- » ur g from time to time. ucts has been calculated in this Laboratory based on the assumptions that the average energy is one-third the maximum energy of the beta particle and that the percentage of ere} isotepe in fallout samples follows the Hunter and Ballou 6 calculations, The average energies calculated on this basis are: “ay 1.