[Phys-L] Detecting hidden nuclear explosives WAS Fun Physics in Space

[Ludwik Kowalski <kowalskil@mail.montclair.edu>]

Those who will be teaching nuclear physics might take advantage of the ongoing debate about the Iranian nuclear situation. How can one detect the strongly-enriched uranium, placed either inside or outside of a bomb? I am sure that nuclear physicists have been addressing this problem, in the context of inspecting vessels arriving to our ports, or crossing our borders.
 
One possible approach is to irradiate a suspected object with a source of slow neutrons (for example, a Cf-252 source surrounded by a moderator, such as pure graphite or paraffin). The slow neutrons, in turn, would induce fission; fission fragments would be gamma radioactive and gamma rays would be detectable from outside the suspected material. Can gamma ray detectors be placed on drones? If not, then why not?

The idea is simple, but it presents some practical difficulties, as always. For example, how can one distinguish gamma rays emitted by fission products in the enriched uranium from the gamma rays emitted by fission products in the Cf-252 source? Will the method work despite the presence of the cosmic background?  Which gamma ray peaks should one concentrate on, and why?  Questions of that kind might also promote critical thinking. Do you agree? 

Ludwik Kowalski, a retired nuclear physicist (see Wikipedia) 

http: //csam.montclair.edu/~kowalski/life/intro.html
=======================================

On Aug 19, 2015, at 10:38 PM, David Marx wrote:

> Colleagues,
>
> If you're teaching a classical mechanics course this semester, you may want to
> use this...
>
> https://www.youtube.com/watch?v=1n-HMSCDYtM
>
> Or, you may just want to have fun with it yourself.
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@www.phys-l.org
> http://www.phys-l.org/mailman/listinfo/phys-l