Zuni, and Tewa. Numerical values are tabulated in Tables B.1 and B.2. Because the records of the TIR’s and the deck (D-TIR) are plotted for the YAG’s, the measurements made by the . TIR’s in the standard platform (P-TIR) have been included in Appendix B. The records of the Ic’s with shorter collection intervals have been omitted, because they show only the greater variability in the fine structure of the other curves and do not cover the entire fallout period. TIR readings have been adjusted in accordance with the calibration factors applying to the four ionization chambers present in each instrument, and corrected to account for saturation loss over all ranges. (The adjustments were made in accordance with a private communication from H. Rinnert, NRDL, and based upon Co gamma rays incident on an unobstructed chamber, normal to its axis.) Recorder speeds have also been checked and the time applying to each reading verified. In those cases where saturation occurred in the highest range, readings have been estimated on the basis of the best information available and the curves dotted in on the figures. ft is pointed out that these curves give only approximate air-ionization rates. Because of ‘the varying energy-response characteristics of each ionization chamber, and internal shielding effects resulting from the construction of the instrument, TIR response was nonuniform with ‘respect both to photon energy and direction, as indicated in Figures A.2 through A.4. The overall estimated effect was to give readings as much as 20 percent lower than would have been re- corded by an ideal instrument. (Measurements were made on the YAG 39 and YAG 40 during ali four shots with a Cutie Pie or T1B hand survey meter held on top of an operating TIR. The TIR’s indicated, on the average, 0.85 +25 percent of the survey meter readings, which themselves indicate only about 75 percent of the true dose rate 3 feet above a uniformly distributed plane source (Reference 17). Total doses calculated from TIR curves and measured by filmpack dosimeters (ESL) at the same locations are compared in Section 4.3.5.) Detailed corrections are virtually impossible to perform, requiring source strength and Spectral composition as functions of direction and time, corrdined with the energy-directional Fesponse characteristics of each chamber. It is also pointed out that these sources of error are inherent to some degree in every real detector and are commonly given no consideration whatsoever. Even with an ideal instrument, the measured dose rates could not be compared with theoretical land-equivalent dose rates because of irregularities in the distribution of the Source material and shielding effects associated with surface conditions. However, a qualitative study of the performance characteristics of ship, barge, and island TIR’s indicated that all per- formed in a manner similar for the average numbers of fissions deposited and identical radionuclide compositions. The exposure interval associated with each IC tray has been carefully checked. In those cases where the time required to count all of the trays from a single instrument was unduly long, activities have been expressed at a commontime of H+12 hours. Background and coincidence loss corrections have also been made. The time interval during which each tray was exposed is of particular importance, not only ause its midpoint fixes the mean time of collection, but also because all tray activities in Counts per minute (counts/min) have been normalized by dividing by this interval, yielding counts ber minute per minute of exposure (counts/min’). Sucha procedure was necessary, because Collection intervals of. several different lengths were used. The resulting quantity is an activity- arrival rate, and each figure shows how this quantity varied over the successive collection inter- vals at the reference time, or time when the trays were counted. If it can be established that 8 is proportional to activity, these ‘same curves can be used to study mass-arrival rate with (Section 3.2.3, Shots Flathead and Navajo); if, on the other hand, the relationship of mass to activity is unknown, they may be used for comparison with curves of mass-arrival rate con- ted by some other means(Section 3.2.3, Shots Zuni and Tewa). Thus, while each point on a TIR curve expresses the approximate gammaionization rate proed at that time by all sources of activity, the corresponding time point on the IC curve gives decay-corrected relative rate at which activity was arriving. Both complementary kinds of information are needed for an accurate description of the radiological event that took place ata one Station and are plotted together for this reason—not because they are comparable in any ‘er way. 43