Anybody know if it's still possible to get thorium mantles of the sort fitted to tilley lamps from any place there days?
It's actually for testing an old Geiger counter that was a Maplin kit.
I'd have guessed that the thorium has been replaced by some other material these days, but I could be wrong.
Don't know, but do you have an old luminous watch or, best of all, the standard War Dept prismatic compass? Mine gives about 500 counts per second. The natural K40 in high potash fertiliser will give you about double the natural background.
Try a smoke alarm. The disc is Americium (alpha source)
Would tritium dials from Trimphones be an acceptable alternative source of radioactivity?
Owain
The message from Jim Scott contains these words:
Just remember to crimp it back again afterwards!
Thanks for the suggestion. I've looked on ebay, and WWII luminous watches are about £20-£30, which is a bit expensive. I didn't know about the potash fertiliser.
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.
"John Nickum" wrote
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 :-)
H
Most valves (out of a nold Telly etc) have thoriated tungsten cathodes in 'em, which might be enough of a source? I'd guess that the electron gun in a tube might be a source, too. IIRC, camping gas lamp mantles are thoriated, TAAW.
I used to work in a big transmitter cabin which had fibre-optics for the control gear, and wondered why we had to replace them every few years, only to be told "Oh, the radiation from the TWT [1] makes them go cloudy..." :o0
Dave H. (The engineer formerly known as Homeless)
[1] Travelling Wave Tube, a big (ie several KW) broadband microwave transmitting amplifier. With a 5KV, 5A power supply. Dangerous. VERY Dangerous.
Don't let Big Clive anywhere near such a thing.
Hmm.. . who says microwaves can't cook crispy food.
Owain
|Anybody know if it's still possible to get thorium mantles of the sort |fitted to tilley lamps from any place there days? | |It's actually for testing an old Geiger counter that was a Maplin kit. | |I'd have guessed that the thorium has been replaced by some other |material these days, but I could be wrong.
If you live in a granite area, Cornwall, Scotland etc, the rock is mildly radioactive. Are you traveling to a granite area sometime soon?
Yes. The cheap Chinese mantles contain thorium, expect 500-600 Becquerel.
Anchor and Egret are mantle brands that are radioactive, Luxor and Petromax aren't.
Just take you Geiger counter into the shop!
Thomas Prufer
According to the article referenced by John Ruum, the tritium would be mixed into a waxy substance - and presumably sealed in glass which would prevent escape of the alpha particles.
Breaking it open could be messy, so I think I'll pass on that one. :-)
"Dave H." I used to work in a big transmitter cabin which had fibre-optics for the
astonishing and quite frightening.
I'm in the Midlands, so it's a long way to travel either way.
Thanks for the info. But using the Geiger counter to select a mantle might not be too clever. ;-)
Getting tritium to emit alpha particles would be a really neat trick, and worthy of a Nobel Prize :-)
Steve S
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.
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