"HLAH" wrote:

"John Nickum" wrote
Thanks. I've just tried monitoring a smoke alarm, but of course, alpha
particles can't go through its plastic case. At least smoke alarms are
cheap, so I'll try breaking one open tomorrow.

Careful now, you will have the anti-terrorist squad kicking your door in
(and maybe shooting you) for trying to build an improvised dirty nuclear
device :-)

Aaagh! ;-)

Anyway, I've broken open the smoke detector and found that it's more
than enough to prove that the Geiger counter is working.

Job done.

If I hold the Geiger counter just 1cm from the source, it really does
thunder, and I have to switch it to its uppermost range, but if I hold
it 5cm away, then it's back to background levels. So it seems that the
smoke detector emits low-energy alpha particles that have low
penetration even through the air, so it's a nice safe test.

--
John