On 22/02/2021 09:40, Chris Hogg wrote:
On Mon, 22 Feb 2021 08:52:28 +0000, The Natural Philosopher
wrote:

At my school we had a Geiger counter, The physics master switched it on.
'why is it clicking?' 'There is natural radiation everywhere'. We played
with it for a bit. Some people seemed to be slightly more radioactive
than others.,

Then the physics master unlocked a box and carefully lifted out two lead
pots put them on the bench and told us to gather round. He used tongs to
lift out one silvery disk and put it on the bench. The Geiger counter
perked up a bit. He took another silvery disk out of the other pot, the
Geiger counter got a bit more interested. He slowly and very carefully
slid one disk towards the other, stopping about 1/8" apart. The Geiger
counter went mad.

"I think that will do" he said. "That was a chain reaction, and those
disks were uranium , somewhat enriched with U235"

"What would have happened if they had touched sir?" "We would all have
been in the Royal Free" he said "And I would have been sacked".

They don't do physics like that any more.

Interesting. But I'm surprised he had access to even slightly enriched
uranium, although back in the day I suppose such things may have been
available through lab chemical stockists for just such demonstrations.
Townson and Mercer is a name that comes to mind. I know that depleted
uranium was fairly easily come by, but not enriched.

Phd Physics from Cambridge. I bet he had contacts at the Cavendish...


Its a shame no one makes cheap Geiger counters on smart phones. Once
people realised how radioactive the world is compared to a nuclear power
station, they would clamour for nuclear power. I guess that's why no one
has put one in a phone. Project Fear needs its bogeymen to keep you
believing in windmills....

I have a small Geiger counter - one of these
https://www.amazon.co.uk/RADEX-RD150.../dp/B005ZQ47AS
not particularly cheap, but interesting to use in Cornwall around old
mine sites where pitchblende was mined. I also have some uranium glass
items made in the 1930's that get it quite excited, and alarmable
friends alarmed :-)

Indeed.



--
Climate is what you expect but weather is what you get.
Mark Twain