cesium-137 gamma abundance

[Rick Rasmussen <rickras@lanl.gov>]

I have a question concerning the yield or abundance for the cesium-137 662
keV gamma.  The lesson plans used here at Los Alamos National Laboratory
(which are written by the DOE) use the 6CEN to get the exposure
rate in R/hr, where C is the activity in curies, E is the energy of the
gamma in MeV, and N is the percent abundance.  The lesson plan uses 85% as
the abundance for the 662 keV gamma and I ahve ssen the 85% used elsewhere.
When looking in books that show the decay scheme for cesium-137 they
indicate that the abundance is 93.5%.

Which one is correct?  Any thoughts on the subject would be appreciated.

Thanks.


Rick Rasmussen
Los Alamos National Laboratory
phone: 505-665-7973
fax:   505-665-4859
e-mail rickras@lanl.gov