Re: Dangers of Pu / Air Activation c.s.

["Dale E. Boyce" <dale@radpro.uchicago.edu>]

David,

Wrt. cross sections for air activation, your best bet is to check with
the nuclear chemistry group at LANL.  I think they are in the INC-11
division unless Los Alamos has reorganized again:).  As I remember
they used to use plastic scintillator as a beam monitor in some of
their work, not as a detector, as a target.  After EOB they would pull
the scintillator and put it betweeen two 3"x3" NaI(Tl) detectors to 
measure the anihillation radiation from C-11.  I have references
at home for higher Z targets, and if all you need is ball park, I can 
probably get you within a factor of two.  References to "greater than
100 MeV" are probably not any better than that.  The reaction mechanisms
are changing rapidly in that regime.  As you go from 50 MeV to about
1 GeV, deeper channels are turning on.  Near target product cross sections
decrease as the deeper product cross sections increase.  For targets
like Aluminum, I think things have flattened out by about 1 GeV.  Even
for heavier targets, the cross sections are pretty constant for radiation
safety purposes.  Nitrogen and oxygen targets production cross sections
probably flatten out at somewhat lower energies.

Dale Boyce
dale@radpro.uchicago.edu