DU, other interactions

[Lester Slaback <Lester.Slaback@NIST.GOV>]

Aside from alpha decay and spontaneous fission (at about 0.006 f/s/gram) 
one also has neutron capture with a 2.7 b cross-section (leading to U-239 
and its decay products, the disreputable Pu-239) and fast neutron fission 
at about 0.6 barns.  The latter two are comparable (but less) to the 
spontaneous fission rate in magnitude at sea level (assuming a geometry not 
shielded from cosmic neutrons).  But at 12400 Bq/g the alpha decay and the 
related gammas from the daughters clearly dominate the process.

Disclaimer:  the above are the personal musings of the author, and do not 
represent any past, present, or future position of NIST, the U.S. 
government, or anyone else who might think that they are in a position of 
authority.
Lester Slaback, Jr.  [Lester.Slaback@NIST.GOV]
NBSR Health Physics
Center for Neutron Research
NIST
100 Bureau Dr.  STOP 3543
Gaithersburg, MD  20899-3543
301 975-5810 voice
301 921-9847 fax

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