I went out on the weekend and bought a smoke detector for only $7AU which has a
nice little alloy disk with americium 241 (according the package). It seems to
emit quite a nice stream of particles from one side using my geiger counter.

I have begun testing this source on a single element Fluorescent test rig I've
set up, the results have been both promising and frustrating, which I'm
currently writing up.

But in summary

1) I've simplified fluorescent tube detector into a simple single tube system
for testing against a radioactive source.

2) Completed a number of tests to illuminated both RFI noise and noise generated
in the electronics and Oscilloscope I've been using to measure the output.

4) The detector produces random pulses unlinked to anything I can isolate.

5) Holding the alpha particle source close increases these pulses and turning it
away decreases.

The frustrating thing is the degree of change is far from what I would expect,
as my Geiger Counter has a marked difference compared with the fluorescent tube
detector. This maybe the large surface area of the detector or something else
generated within the tube.

But then again the aim of this project is cheap and easy, and the sensitivity
not matter when linked in coincidence circuit and filtered and spaced to only
pluck out high energy particles.

I'm currently looking a different tube manufactures and wattage, I will also
break one open to see if the filaments are doped with something to help excite
ionization. As I have read that Neon Lamps often use a tiny bit of thorium, and
this maybe what is causing the high background noise.

Feedback, ideas, assumptions always very welcome.

Regards

Robert