[Rodrigo]

Rodrigo asked the Naked Scientists:
   Dear Dave,
I am fascinated with the cloud chamber experiment. This made particle physics a bit more real to me, and I loved it! Trying to follow the thoughts of the pioneer particle scientists, a few questions came to my mind:
1) Has the cause of the condensation necessarily be the presence of sub-atomic particles? Couldn't it be a whole atom or molecule, remaniscent of some spontaneous chemical reaction?
2) I believe these sub-atomic particles to be ridiculously fast, to the point that we wouldn't be able to tell, by looking  at the wake, if they were coming or going. It seems, though, that we can tell whether they are coming or going... How come? What is typical speed of these particles?
Thanks a lot, I love the show.
Rodrigo
Brazil.
What do you think?

[daveshorts]

There are lots of other things which can trigger condensation, but they are almost all local, or random - at least they won't cause a line of condensation. I don't know anything other than charged particles which
will cause these lines of condensation you see in the experiment.

My guess has always been that it is some form of optical illusion, either that or one end of the track is slightly more supersaturated than the other, so that although the whole track was essentially formed at once, the cloud grows faster at one end, and therefore you see it first

[christopheschram]

Hello,

I'm working in acoustics, and I was wondering if anyone had heard of an application where the condensation in a cloud chamber could be triggered by an acoustically-induced pressure variation ?

Any suggestion welcome!

Thanks,

Christophe.

[RD]

I'm working in acoustics, and I was wondering if anyone had heard of an application where the condensation in a cloud chamber could be triggered by an acoustically-induced pressure variation ?

Any suggestion welcome!

The sound vibrations could cause the droplets in the cloud to become concentrated in patterns, like the sand on a Chladni plate, (but the patterns in the cloud would be three dimensional).



http://www.physics.ucla.edu/demoweb/demomanual/acoustics/effects_of_sound/chladni_plate.html