Sper Scientific 840007 Radiation Detection Meter - Manual (Page 4)

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sonable average time should be at least two minutes or
more.
The Geiger-Mueller tube is located behind the slots in the
upper edge of the case. The surface of the tube is very thin
(0.004"). This allows beta radiation to penetrate and to be
detected with greater efficiency. (Beta rays and other types
of radiation will be discussed in the next section). This thin
surface is fragile and poking sharp objects through the slots
will damage the tube.
Your Geiger Counter is designed to be sensitive to:
1. Gamma radiation (which includes X-rays).
2. Beta radiation.
FIG. 1
Gamma radiation and X-rays can penetrate the plastic case
with comparative ease.
Beta radiation can most efficiently enter the case through
the slots. Although Beta radiation is easily detected, it is
difficult to measure accurately. Therefore, when a radioac-
tive object is being searched for Beta radiation, the open
slots in the case should be positioned in such a way that
they are exposed to the object (see Figure 1).
If the unit shows a significantly higher click rate in this posi-
tion, you can be reasonably certain the object is giving off
Beta radiation.
Now position the unit as shown in Figure 2. In this position,
where radiation cannot pass directly through the slots (Beta
radiation travels in straight lines for the most part) only
gamma and X-ray radiation from the object will be de-
tected.