ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
*****************************************************************************

Hi everyone,

We're knocking around the idea of building an exhibit based on the 
Crookes Tube -- you know, those physics-lab cathode ray tubes, like 
this:

http://www.uvm.edu/~dahammon/museum/crookstubes.html

(Basically, we'd like visitors to be able to deflect a particle beam 
with a magnet -- to be able to do on a small scale what Ernest 
Lawrence did on a grand scale.)

A couple of questions:  Has anyone ever seen such an apparatus as a 
standalone exhibit?  I've personally only seen them in physics labs, 
and I haven't been able to find any references to hands-on exhibits 
(as opposed to Crookes tubes in museum collections; the Web is lousy 
with those...).

A related but more important question: Would this be safe?  I found a 
paper from 1967 that seems to indicate that the X-ray emission from a 
Crookes tube is pretty stunningly high, regardless of whether you're 
measuring in front of the unit or off to the side.  Unfortunately, 
the paper doesn't give details like the voltage they're driving the 
tube with or other information like that, but I'm starting to get a 
sinking feeling of "UNDER NO CIRCUMSTANCES can we do this on the 
floor" (short of sealing the exhibit behind leaded glass or 
something)....

I'd appreciate hearing about any experiences or lab safety knowledge 
anyone would like to contribute!  Thanks much,

--Allan



-- 
~~

Allan Ayres
Exhibit Developer
Lawrence Hall of Science
University of California, Berkeley
Berkeley, CA 94720-5200
[log in to unmask]
510-642-1254

***********************************************************************
For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.

Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.

The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
http://www.lsoft.com/LISTSERV-powered.html.

To remove your e-mail address from the ISEN-ASTC-L list, send the
message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
[log in to unmask]