SHADOW is a small, high quality survey meter with a standard 2"
pancake GM detector mounted on the bottom. No external probe is
needed to do contamination monitoring. Surveying can be done with
only one hand and the instrument is small enough to fit in a lab
The SHADOW has three linear ranges of 500, 5,000, and 50,000 CPM
which are chosen by a three position toggle switch. The scale is
also calibrated in mR/h for approximate gamma radiation with ranges
of 0-0.2, 0-2, and 0-20 mR/h. The beeper is controlled by the power
switch, and the meter light is turned on by a momentary push button.
The SHADOW has a unique, QR Quick Response feature which
eliminates the need for an adjustable time constant. This circuit
adjusts the time constant dynamically. When the counting rate increases,
the meter will quickly move up scale then slow down as it approaches
the true value. The same action occurs if the counting rate decreases:
the meter will go down scale quickly then as it nears the true value
it will slow down. The feature reduces the statistical meter fluctuations
at low counting rates while still responding quickly to significant
changes in the counting rate.
The SHADOW automatically checks the battery condition every time
the meter is turned on. When first turned on the meter reads the
battery condition for a few seconds then the instrument beeps if
the battery is OK.
The Shadow is a very useful convenient meter. Anywhere where the
potential for contamination exists, there is a need for the Shadow.
3" x 6 1/4" x 1 5/8" (75mm x 159mm x 40mm)
oz. (500 grams)
2" Pancake GM Tube
2 ½" Taut Band Meter
Controls: ON-OFF-ON WITH SPKR toggle switch, Range toggle switch
X1, X10, X100 (500, 5000, 50000 CPM), Lamp push switch
Controls: Calibrate adjustments X1, X10, X100
Detected: Alpha >3 Mev, beta >45 KeV, gamma > 6 Kev, Xrays
0-5000, and 0-50000 CPM (Scale also calibrated for approximate gamma
dose rates from the side: 0-0.2, 0-2 and 0-20 mR/h)
Material: 1.5- 2.0 mg/cmE2, Mica
Quick Response Time Constant: Uses fast TC to get close to reading
then changes to slow TC.
Approximate Efficiencies: Tc99: 25% Sr90: 45% C14: 12% (based
on 4p geometry)
Beeper: Piezo Electric. Beeps every count with power switch in
ON WITH SPKR position, beeps only at turn-on in ON position. Beeps
at turn-on if battery is good.