Monitoring Personnel

TM 11-6665-245-12

a . Remove the main probe from the

NOTE

radiacmeter by loosening the handle retaining nut

In certain situations, it is inconvenient

and sliding the two apart.

to constantly watch the indicator meter

f o r radiation. I n those cases, the

NOTE

operator should wear the headset. Con-

In the following procedure, the photo-

nect the headset to the headset connec-

multiplier tube in the main probe handle

tor on the radiacmeter and listen for the

will be uncovered. It must not be ex-

sound of clicks generated by radiation

posed to any light at all when the equip-

detected by the main probe (or aux

ment is OFF, or exposed to any light at

probe). When listening in an area of no

all when the equipment is ON. Such ex-

radiation, random clicks (below 100

posure will damage the photomultiplier

CPM) are heard. As an area of radiation

t u b e and shorten its life. Take the

is detected by the probe, the clicks

following precautions:

c o m e much faster and are accom-

panied by higher meter readings.

Change the main probe with aux

probe in a darkened room. Set the

(4) When an area of radiation is detected

selector switch to OFF or remove

by the main probe (or aux probe), the CPM reading

batteries.

on the indicating meter will increase. Shift the

selector switch to the 10K, 100K, and 1M posi-

tions as the indicating meter needle moves off the

b. Remove two binder head 1/4 inch screws

scale.

(Figure 2-5) from the main probe handle (below the

cable connector). Retain the screws.

NOTE

c . Grip the handle and the main probe body on

each side of where they separate (right above

When changing to higher measurement

where the screws were removed). Slowly pull the

positions, the indicating meter needle

two apart using a twisting motion.

might remain to the right (off the scale).

d. Remove the plastic plug from the aux probe

In this case, press the METER RESET

and insert it into the large probe opening.

switch.

e . Slip the aux probe over the photomultiplier

tube exposed in c above and rotate while slowly

c. Procedures for Using the X-Ray Probe. Per-

pressing it onto the handle. Line up the holes in

form Operator Check of X-Ray Probe (Para. 2-2.b)

the aux probe with the screw holes in the handle.

and use the following procedure for monitoring

Replace the two binder head screws in the han-

areas suspected of low energy gamma radiation

dle.

contamination.

NOTE

WARNING

There is no waiting time after connec-

The check source used in this equip-

ting the x-ray probe.

ment contains Thorium (a radioactive

metal). Thorium is a hazardous material.

(1) Slowly scan with the probe window 6 to

Injury or disease may result if the check

12 inches from the suspected object or area.

source is not handled properly. Use ex-

(2) The extension handle may be attached

treme care not to touch, scratch, break,

to the x-ray probe by removing the probe and in-

or remove the surface of the check

serting the extension between the handle and the

source while handling them. See the

probe.

front of this technical manual for first

(3) Operate on the most sensitive range

aid procedures.

that does not result in an off-scale meter reading.

f. Test the aux probe for light tightness as

2-4. Monitoring Personnel

follows:

(1) Perform initial procedures of installing

The aux probe is used to monitor personnel or to

batteries, checking batteries, and placing the aux

be used in confined spaces for monitoring where

probe against the check source as in paragraph

the main probe cannot be used. The aux probe is

2-2 to determine proper operation.

installed in place of the main probe on the main

probe handle prior to use.

Change 2

2-3