4.
Principles of Operation.
When gamma radiation strikes the silver phosphate glass contained
within the DT-236/PDR-75, the electrons within the glass are raised to
a higher energy level where they are trapped. As ultraviolet light is
applied, the atoms of the glass fluoresce or emit visible light. The
intensity of the visible light emitted is directly proportional to the
amount of gamma radiation the glass has absorbed. The neutron
detector has a semiconductor diode. Its lattice structure is damaged
by the neutrons colliding with it. The lattice damage increases the
electrical resistance of the diode. Since the resistance has
increased, any voltage applied across it will result in increased
voltage drop. This increase is proportional to the neutron dose
received.
5.
Operate the AN/PDR-75 RADIAC Set.
Prepare the reader for use prior to reading dosimeters. Adjust the
reader prior to reading dosimeters every 1/2 hour during operation,
and any time the ambient temperature changes more than 5 F (2.8 C).
a. Preparation for Use.
To prepare the AN/PDR-75 RADIAC Set for use, follow these steps:
Step 1.
Set carrying case on end opposite front cover flap.
Step 2.
Unfasten two straps (1) on front cover of carrying
case by pulling short release tab (2) on each buckle.
Open case by lifting front cover flap (3), (Figure 5-
24).
Step 3.
Stand on the side of carrying case opposite the front
cover hinge (4) and place both feet in carrying case
handles (5), ( Figure 5-25), on either side of case.
Standing on the handles will keep the case stationary
as you withdraw the reader.
Step 4.
Grasp the reader removal strap (6), (Figure 5-25),
with one hand, and grasp the reader at the edge near
the front panel assembly with the other hand.
5-25
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