Re: Particle & Nuclear Physics for HS Teachers

[Bernard Cleyet <anngeorg@PACBELL.NET>]

I couldn't believe it when I learned the U (Santa Cruz) got rid of their 10 Ci.
Pu-Be source.  Yes, Ag, two nuclides, makes an excellent source because one is
about two and a half minutes and the other ~ 24 sec. easily separable graphically
or by computer aided fitting (e. g. Kaleidograph or Vernier's GA).   There are a
number of variations possible, e.g. varying the activation time, position in the
moderator, "shielding" with Cd, etc.  The "cow" to which Ludwik refers is (was?)
advertised in TPT.   One may do it yourself using Zr phosphate ion exchange resin
eluting with 1 M HCl.  See J .J. Pinajian "Journal of Chemical Education"  V. 44
#4 (1967) pp. 212-213.  I expect there are better, more recent references.  My
reference (Experiments in Nuclear Science) is two pages -- mailed to Squeaky
People.

My bathroom fan collects much dust (because of the high humidity), which I found
disturbingly radioactive.

Another fun one was (I'm repeating?) measuring the activity of mushrooms I
collected in Sweden.  My guide claimed a particular specie was very efficient in
Cs uptake -- he's correct!

bc

P.s.  I don't think that it is the ions attracted, but the dust, which contains
the ions, just as tobacco smoke contains the radon that selectively kills smokers
(miners mainly).

Ludwik Kowalski wrote:

> 1) I also recommend the Vernier counter and its software.
>
> "Frohne, Vickie" wrote:
>
> > ... For high school student use, you can get new geiger counters for around
> > $200 from Vernier. http://www.vernier.com They can be used either with the
> > Vernier computer interfaces & Logger Pro software, or as stand-alone
> > counters.  Vernier also has a book of experiments to go with their counters.
>
> 2) Another thing you would appreciate is a source whose half-life
> is not too long. We have a Pu-Be neutron source and I can easily
> make such sources. Ask around, perhaps they have one too.
> Another approach is to purchase a kit in which a long T material
> is in equilibrium a short T material. The short T material is soluble
> and can be "milked out" for experiments. The third alternative is
> to concentrate radioactivity from air. Several years ago Walkiewicz
> described a very effective way of doing this; it was in The Physics
> Teacher. He used an ordinary charged balloon. A good project
> for future teachers.
>
> A wet tissue collects enough radioactivity (several times the GM
> background) from a dusty TV (or computer screen) to observe
> the decay for many hours. If I recall correctly, it was a mixture
> of two components: T~11 hrs and T~1 hr. This is because the
> screen is charged and radioactive ions are attracted to it.
>
> 3) I used to take students to a field trip to a local Veterans
> Hospital which had a good nuclear medicine department.
> Look around for something of that kind.
> Ludwik Kowalski