Radiac Detector DT-196/PDR27R. (fig. 1-2) (2).

TM 11-6665-230-12

b. Radiac Detector DT-196/PDR27R. (fig. 1-2) (2).

The mica window of the probe is 0.0005 inches thick, and It is extremely fragile.

Do not touch the window under any circumstances as the Geiger-Mueller (G-M)

tube will be damaged. Do not rely upon the guard ring to protect the mica win-

dow. The guard ring openings are large enough so that sharp objects may pierce

the window.

1. The radiac detector is a probe consisting of MlL-type 5979 and 5980 Geiger-Mueller (G-M)

tubes, each enclosed in a separate metal housing, The two housings are clamped together into one unit.

A movable metal shield normally covers the mica window of the larger tube. When the shield covers the

window, beta radiation is excluded from the tube. The shield can be swung aside when beta-plus gamma

radiation readings are desired.

2. Electrical connections for both Geiger-Mueller (G-M) tubes are made at the ends of the

metal housings where the shielded cables pass through waterproof packing glands to the tube elec-

trodes. The probe cable is flexible and kink proof and is normally coiled in the space on top of the handle.

c. Radioactive Test Sample MX-7338/PDR-27R. (fig. 1-2) (3).

Krypton-85 is a gas which is radioactive, emiltting beta and gamma radiation. In

this test sample, the shielding permits only the gamma radiation to escape.

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