Date: Wed Mar 4 15:49:59 2009

Author: Bill Norwood

Subject: Re: Cloud Chamber Hallway Demonstration


Hi Taplers, I also have signage I could share. Bill Norwood

-----Original Message-----
From: [] On
Behalf Of
Sent: Friday, February 27, 2009 2:57 PM
Subject: Re: [tap-l] Cloud Chamber Hallway Demonstration


This was the signage I put on it:

E. T.s?

This is a cloud chamber. It contains alcohol that has been cooled so
that above the black plate at the bottom, there is a saturated cloud
of alcohol. When an energetic sub-atomic particle passes through the
cloud it leaves a trail of ionized atoms upon which the alcohol
condenses leaving a vapor trail. Many of the trails you see are caused
by cosmic rays which may have traveled through intergalactic space to
reach Earth; these rays strike atoms in the Earth?s upper atmosphere
and cause a shower of other particles which form the trails in the
cloud chamber. Every now and then you will see a thick, straight,
short (an inch or two) trail which is probably the result of a radon
atom decaying and giving off an alpha particle (the radon comes from
uranium decay in our soil).


Quoting "Zani, Gerald" :

> Cliff,
> Nice!
> The reason I originated this thread and had asked specifically about the
> hallway cloud chamber at Caltech was that I was told the chamber did not
> have a particle source. It was for viewing just Cosmic Ray muon tracks.
> And I was told there was a magnet that a viewer could take and hold up
> to the chamber and deflect the Cosmic rays to curve the track.
> It's Friday! - J
> -----Original Message-----
> From: [] On
> Behalf Of
> Sent: Friday, February 27, 2009 12:06 PM
> To: tap-l
> Subject: [tap-l] Cloud Chamber Hallway Demonstration
> I am giving a talk on radon to a citizens group on Monday so I had
> taken my cloud chamber out to prepare for my presentation. Since I had
> it out anyway, I thought I might as well set it up so passersby in the
> hall could see tracks. I put a TV camera on it and placed a monitor in
> my hallway door. It has proven to be quite popular, a couple of
> students even asking to enter my lab so they could see the apparatus
> up close (I used the TV camera so I could avoid reflections from
> lights on the viewing window).
> Cliff