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Chapter 11: Basics of Taking Measurements
The Inspector EXP will not detect neutron, microwave, RF (radio frequency), laser, infrared, or ultraviolet
radiaon. All of our instruments are most accurate for Cesium-137 and isotopes of similar energies. Some
isotopes detected relavely well by most Geiger counters are Cobalt-60, Technicium-99M, Phosphorous-32,
Stronum-90, and many forms of Radium, Plutonium, Uranium, and Thorium.
Some forms of radiaon are very dicult or impossible for a Geiger tube to detect. Trium, for example, is
a by-product of a nuclear reactor and is used in research. The beta emissions from Trium are so weak that
there are very few instruments that are capable of detecng it. More sophiscated equipment is needed for
the measurement of environmental samples, such as radioacvity in milk, produce, soil, etc., unless you are
looking for gross contaminaon.
The radiaon from some isotopes can cause a Geiger tube to overexcite and indicate a higher level of radiaon
than is actually present. Americium 241 is an example of this phenomenon. Americium 241 is used in some
smoke detectors and many dierent types of industrial density and ow meters.
Unless you know exactly what you are measuring and understand the limitaons of detecon instruments,
it is possible to draw misleading conclusions from your readings. We design our instruments to detect the
broadest range of ionizing radiaon possible and sll be aordable. The full spectrum of ionizing radiaon
cannot be measured by one single instrument. Everyone agrees that radioacve materials can be dangerous.
We encourage you to seek out other sources of informaon.
How to Detect Background Radiaon
To see what the background radiaon is in your area, simply turn the instrument on and, aer the 30 second
start up beep, the general background radiaon will be displayed.
How To Survey a Surface
When surveying a surface, such as a counter top, you will need to hold the Inspector EXP about 1-2
cenmeters from the surface while moving the unit horizontally across the survey area at a rate of 2 inches per
second.
How to Perform a General Survey
A general survey would be used to nd a potenal source. For example, if you are looking for a potenal
source in a pile of scrap, the Inspector EXP will typically detect about 2 feet into a pile. It is easier to nd a
source when the Inspector EXP is set to Fast Response mode. However, even if the Inspector EXP is in Auto-
Averaging mode, the audio clicks that indicate a count should be a sucient indicator if a potenal source is
present. To nd the source, slowly move the Inspector EXP in the direcon of the higher readings or clicks unl
the potenal source is found.
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