It is hardly to get geiger muller tube. The domestic manufacturer discontinued the products. It is expensive even if available.(C)2004-2006 All rights reserved by Y.Onodera.
It is restricted also overseas. In fact, one atmospheric pressure is also measurable using air.
However, the high voltage of 3000V to 5000V is required (influenced by the caliber).
Sensitivity can be made high, so that a caliber is large.
Since most in air is the nitrogen near inactive gas, it becomes substitution of inactive gas.
Composition in air
Nitrogen 78.08% Oxygen 20.95% Argon 0.93% Carbon dioxide 0.035%
Butane gas (gas of a lighter) is used instead of halogen gas as continuation electric discharge prevention gas.
Alcohol is sufficient.
It is for preventing those without electric discharge (equivalent to the oscillation state said in an electronic circuit).
As for electric discharge, sparks do not come out. By the eye, it cannot check.
(Oxygen changes to ozone by electric discharge.)
Comparison Geiger muller tube Air geiger muller tube Inactive gas Ar, He N Continuation electric discharge prevention gas Halogen gas Butane gas Inner pressure 0.1 Atmospheric pressure 1 Atmospheric pressure Operation voltage 500-700V 3000-5000V Window Mica Kitchen wrap