of 10 r.
The agreement of the calibration from 1 to 10 r using the two Sources was satisfactory,
the difference being less than 1 percent.
The photographic-transmission densities were read on a film densitometer designed by the
Los Alamos Scientific Laboratory and built by the Eberline Instrument Corporation.
2.2.3 Radiac Detector DT-60/PD. Approximately 160 personnel dosimeters (DT-60/PD),
four to a location, were used at positions indicated in Table 2.1. This gamma detector covers
an exposure range from 0 to 600 r.
The detectors were read before the shot on a calibrated
standard reader to determine predose readings.
2.2.4 Glass Needles. Approximately 160 glass-needle, phosphate-glass dosimeters, eight
to a station, were used to measure the total gammadose at positions indicated in Table 2.1.
The dosimeter consisted of a small glass phosphate needle inside a teflon sleeve, which in tura
75 ips
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Figure 2.10 Block diagram of Kaiser playback-and-readout equipment.
was encased in a lead shield with walls 2 mm thick.
After exposure to gamma radiation, the
response of these glass dosimeters was indicated by an increase in fluorescence upon illumination by ultraviolet light. The glass needles were air mailed to Brooklyn Naval Shipyard immediately after the shot so that the indicated dose could be ascertained.
2.2.5 Gamma Radiation Fallout Detector (MG-3). The MG-3 is a battery-powered, selfrecording set. It was designed and fabricated by Technical Operations, Inc., under contract
with the Air Force for the purpose of studying the use of such a unit as a part of an integrated
fallout-countermeasure system. Thi§ instrument measured X- and gamma-ray dose rates from
1.0 to 1,000 r/hr with an accuracy of +10 percent of the indicated reading.
The sets consisted of ruggedized detector, indicator, and recorder units (Figure 2.13). The
detector unit had an ion chamber for the sensing device. In common with all ion chambers, ion-
izing radiation caused a flow of current whenever there was a voltage across the ion chamber. In
this case, there was a nonlinear relation between the amount of radiation and the amount of current. This relation was fixed by the geometry of the chamber and the fact that the chamber was
operated in a nonsaturated region, i.e., the voltage was inadequate for collecting ions as fast as
22