Appendix 8 DETAILS of MAJOR INSTRUMENTS B.1 AERIAL RADIATION DETECTOR, HASL TH-10-B output of the telemeter is a 1,000-cps tone, gated on and off within a l-second cycle. The Top Hat aerial radiation detector is a scintillation detector utilizing plastic phosphors. The phos-~ input de signal. phors are coupled to photomultipher tubes, and the integrated current output is amplified by a dc amplifier. The amplifier has a logarithmic response and covers a 4-decade range of radiation intensity. By switching between two photomultipliers which have different-size phosphors, two ranges of 4-decades each are achieved: sec. The tape is then manually shifted to a playback recorder, which runs at 30-in/sec. The recording reel, containing up to 30 minutes of data, is played The radiation calibration of a typical back through the radio transmitter in less than 4 Both phosphors are colli- minutes. mated by an annular lead shield, which was adcec to An electronically regulated power supply, HAS uw reduce the effect of aircraft contamination. TB-6-A, supplies all the voltages to the telemeter ahd For a more detailed description of the instrument, the detector control assembly. see Reference 11. The regulators com- pensate for the varying 28-volt input power from the aircraft generators. B.2 ALTITUDE COMPENSATOR The telemeter central station is connected to the earphone output jack of a receiver, which 1s tuned to The surface radiation reading, R; is related to the aircraft reading, Ra/c, by a constant, fg, which deThus, Ry the transmitter frequency. = bels of radio noise above the signal level. Ra/c x f,- However, the circuit current is related to the logarithm of Ra/c, and the altitude, h, is propor- This is followed bx a conventional ratemeter which converts tional to the logarithm of fg. The indicated multiplication can be performed bythe addition of the logarithms: = la/e t+ kh The input to the central station has a noise filter, designed to reject 54 deci- (200 <h <1,000) the bursts of 1,000-cps tone to a deflection of the pen on a strip-chart recorder. B.4 AUTOMATIC GAMMA MONITOR, HASL TN-4-C lis a current measured in milliamperes The automatic gamma monitor is based on a detec- k is a circuit constant tor similar to the Top Hat aerial radiation detector. The altitude-compenstion circuit electrically adds an A plastic phosphor is optically coupled to a photomul- altitude signal, derived from the aircraft radio altim- tiplier, whose output is converted in a dc amplifier to eter, APN-1, to the output of the detector circuit. a logarithmic response. The The unit reproduces a radia- tion range from 1 mr/hr to 10 r/hr on a single scale. aircraft radiation reading is continuously modified for changes in flight altitude, and the surface readings re- The output is continuously recorded on un Esterline main proportional to the gamma intensity at 3 feet above Angus strip-chart recorder. the surface. 115-volt, 60-cps current and is completely sealed in an immersionproof case. B.3 TELEMETER, The monitor operates on HASL TT-3-X B.5 SCINTAMETER SURVEY METERS The telemeter is connected in series with the stripchart recorder and converts its drive current, @ to] ma direct current, to an alternating-current wave form suitable for transmission through audio circuits. The DOE ARCHIVES The scintameters are portable surve, mcters that are powered by dry batteries and are completely selfconta:ned. 63 EE IE RETETTTNE©EE ase; Ne a pends on the height above the surface. Where: Also, the tone, is recorded on a tape recorder running at 3%q-in/ The output of each range varies from 0 to 1 ma and drives a strip-chart recorder, Esteriine R3 A high-fidelity transmitter, U.S. Naw ART-13, was used in the P2V-5 aircraft. It has an output power rating of 100 watts. Continuous operation 1s not possi- Therefore, the telemeter output, the gated 1,000-cps The A phosphor is 3 inches in diameter and 3 inches unit is shown in Figure B.1. transmitter or stored on an audio tape recorder. transmitted signal blocks the receivers in the aircraft. high, and the B phosphor is iy, inches in diameter and Angus Co., AW. These bursts of 1,000 cps maybe coupled directly into the microphone input of a radio ble because of heat dissipation limitations. Range A, 0.01 to 100 mr,/hr, and Range B, 10 mr’hr to 100 r/hr. % inch high. The ratio of on to off time within the 1-second time interval 1s proportional to the