Alpha and Beta radiations are surprisingly abundant in nature. The third
variety of radiation, Gamma, is more commonly associated with
artificially produced radioactivity. The one device suitable for
detecting radiation, in all its forms, is the Geiger counter. Once an
expensive instrument, a Geiger counter can actually be built by a
dedicated hobbyist. Assembling your own Geiger counter can be a
fascinating exercise
in discovery. Everything from antique watches to bricks let off small
amounts of radiation that can be detected with the fully-capable Geiger
counter outlined below.
Purchase a Geiger-Muller tube. This is the Geiger
counter's most important component and the only one that cannot be
built from scratch. This sealed cylinder is filled with neon, argon and
halogen. A mica window caps one end of the tube, allowing for the
entrance of radioactive particles. Current is applied to the gas
mixture. The electrical state of the gas mixture is subtly altered
whenever outside particles excite the cloud of atoms inside the tube.
The reactions are then recorded as electrical pulses. Geiger-Muller
tubes are sold by a variety of scientific suppliers (see Resources
section).
2
Etch the circuit board. Building
your own custom Geiger counter requires a proprietary circuit that
helps route the proper amount of power to the anode of the Geiger-Muller
tube, so you need to follow a proper schematic to etch a circuit board
(see Resources section). Begin by drawing your circuit onto the board
using permanent marker. Then mix a 2 to 1 combination of hydrogen
peroxide and hydrochloric acid in a shallow tub. While wearing gloves,
place your board in the acid solution and let sit for 2 to 3 minutes.
The solution should turn a cloudy green. Remove your circuit board and
rinse under cold water. The copper should have dissolved away except
along your marker lines. Wash off the permanent marker and you should
see the copper forming the necessary schematic lines.
Etch the circuit board. Building your own custom Geiger counter requires
a proprietary circuit that helps route the proper amount of power to
the anode of the Geiger-Muller tube, so you need to follow a proper
schematic to etch a circuit board (see Resources section). Begin by
drawing your circuit onto the board using permanent marker. Then mix a 2
to 1 combination of hydrogen peroxide and hydrochloric acid in a
shallow tub. While wearing gloves, place your board in the acid solution
and let sit for 2 to 3 minutes. The solution should turn a cloudy
green. Remove your circuit board and rinse under cold water. The copper
should have dissolved away except along your marker lines. Wash off the
permanent marker and you should see the copper forming the necessary
schematic lines.
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