base required to return the overlaying acidimetric dye to its preirradiation pH value was a measure of the acid produced by the absorbed dose. Use of predetermined data for the system in re- spect to sensitivity to Co® gammaradiation (namely the milliequivalents of acid produced per ml of chlorinated hydrocarbon per r absorbed) and division of these values into the acid produced by the unknown exposure yielded the gamma doses in r. The Air Force dosimeters from Shots Cherokee and Zuni were read in the field by Ist Lt. S.C. Sigoloff, USAF, of Project 4.1. The remainder of the dosimeters were forwarded to the United States for reading and evaluation by the furnishing agency. 2.2.4 Radiac Detector DT-60/PD: Project 2.72 supplied 175 DT-60’s, which were exposed to Shots Flathead and Navajo. Those exposed to less than 600 r were read on site, while the ones exposed to larger doses were read and evaluated at the Naval Medical Research Institute. v »~ Sb ce © Oy ~_ ® Eostmen $48-00¢ @ Eastman 548-0 SC 4 2 b ° ' ol 0 io~ aa 19° 1 2d dt Exposure , roentgens 10° 1 I pi pit 10° Figure 2.3 Cocalibration curves for film types. (Film in NBSholder.’ These dosimeters have an accuracy of about 20 percent. (A technical description and an evalu- ation of this instrument is found in References 16, 17, 22, and 23.) 2.2.5 Radiac Set AN/PDR-39. These instruments, calibrated with Co®, were used to meas- ure the exposure rate in fields of residual-gamma radiation whenever these fields would affect the data. The AN/PDR-39 was a military standard, field-type, portable instrument used for detecting and measuring gamma-exposure rates (Reference 24). Evaluation of the TIB (AN/PDR39) in WT—1138 (Operation Teapot Project 6.1.2) applied primarily to earlier-time residual fields (up to H + 50 hours). Since Operation Redwing Project 2.1 used these instruments in re- sidual fields at H + 80 to H + 100 hours, the errors noted in WT—1138 would be somewhat smaller. The AN/PDR-39 had an accuracy of about 20 percent. 2.2.6 Quartz~Fiber Device (Rate Device) for Exposure Versus Time. This device incorporated eight quartz-fiber dosimeters connected to a battery of zeroing potential. The dosimeters 17