Re: Cloud chamber mystery

[brian whatcott <inet@intellisys.net>]

At 14:02 2/4/98 -0800, you wrote:
> 	If that was a sealed source I doubt that you will see many
> positron tracks....they will mostly annihilate in the material around the
> source.  To see them you need to deposit a very thin layer of a positron
> emitter on a substrate.
>
> Mark
>
> Dr. Mark H. Shapiro

My knowledge of this topic is not great.
But enough to suggest that most positrons are thermalized before
 annihilation - production of which is a prime use of 11Na22 -
the prototypical artificial radio isotope.
 I would expect about the same range as from an electron -
enough to penetrate the capsule.

Brian
brian whatcott <inet@intellisys.net>
Altus OK