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>Build Your Own Geiger Counter, Page 1
Build Your Own Geiger Counter
In this tutorial will build a fully functional Geiger Counter capable
of measuring the three primary forms of radiation; alpha, beta and
gamma radiation. The counter is sensitive enough to detect background
radiation. In the second part of this tutorial we will enhance our
basic Geiger Counter by adding either a Analog Meter or Digital Meter
and a suitable serial port to connect to a windows PC. The windows
98/XP program is free and available for downloading, more on this
later.
The
Geiger Counter produces an audible click and blinks a LED each time it
detects a radioactive particle. Typically the counter clicks 10-20
times a minute due to normal background radiation. While the device is
sensitive enough to measure background radiation, it is not suitable
for measuring radon gas. There are Radon gas detectors that use an
activated charcoal filter that are easy to use and more accurate.
Radioactivity
Radioactivity
is the spontaneous emission of energy from the nucleus of certain
atoms. The most familiar radioactive material is uranium.
There
are three forms of energy associated with radioactivity; alpha, beta
and gamma radiation. The classifications were originally determined
according to the penetrating power of the radiation, see Figure 1. Our Geiger Counter can detect the three types of radiation; alpha, beta and gamma radiation.
Figure 1. Penetration strength of radiation
Alpha
rays are the nuclei of helium atoms, two protons and two neutrons bound
together. Alpha rays have a net positive charge. Alpha particles have
weak penetrating ability, a couple of inches of air or a few sheets of
paper can effectively block them.
Beta rays
were found to be electrons, identical to the electrons found in atoms.
Beta rays have a net negative charge. Beta rays have a greater
penetrating power than Alpha rays and can penetrate 3mm of aluminum.
Gamma
rays are high-energy photons. This has the greatest penetrating power
being able to pass through several centimeters of lead and still be
detected on the other side. Thick lead is needed to attenuate gamma
radiation.
Build Your Own Geiger Counter pg 2 "Geiger Mueller Tube"
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