Hello everyone,

Recently I learned my neighbor has high levels of Radon in their basement
(they installed a mitigation system). Naturally, I was curious as to the
level in my own basement and purchased an electronic radon meter [1] from
the local hardware store [2]. Testing shows that my basement has a
concentration of roughly 20pC/L. (I am currently working on reducing the
level)

One inconvenient aspect of the electronic meter it does not provide an
instantaneous reading. It takes 48 hours to obtain the first reading. And
all subsequent readings are provided by the meter as a long term average.
That got my thinking: can I build my own Radon (alpha particle) meter?

As I understand it a electronic Radon sensor is essentially a large spark
gap. A potential is applied across the gap and when Radon gas decays it
emits alpha particles which causes the air in the gap to ionize - causing a
momentary spark across the gap. With this type of sensor I would assume the
level of radon gas is proportional to the number of sparks across the gap
per second.

I would like to learn: what it would take to design my own radon gas meter?
(For fun, not commercially) Any advice or links to resources (formulas,
charts) would be greatly appreciated.

I have not torn apart/reverse engineered my meter yet because I do not want
to alter the calibration. The documentation states that the sensor voltage
in my meter is 250 volts (DC?). I would assume higher voltages and larger
spark gap areas would yield higher sensitivity. I would have to wonder if
dust and other contaminants would be an issue for this type of detector?

[1] SafetySiren Pro Series 3 Radon Gas Detector, Claims initial accuracy of
20% or +/-1pC/L (whichever is greater).
[2] Home Depot

--=20
Jason White
--=20
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