Pa-234m and Equilibrium in Granite

["Frame, Paul" <FRAMEP@ORAU.GOV>]

For what its worth:

The latest published value for the intensity of the Pa-234m 1001 keV gamma
is 0.835% -  see A.C. Nzuruba "Evaluation of absolute gamma ray emission
probabilities in the decay of Pa-234m"  in Nuclear Instruments and Methods
in Physics Research A 424 (1999) p 425-443.

Regarding the comparison of Pa-234m with Bi-214: as was mentioned by Bruce,
there are coincidence losses to deal with. Perhaps it would be better to
compare Pa-234m with the activity of Pb-214. The latter has lower energy
gammas that are more subject to self absorption, but the coincidence losses
are relatively absent.

Corrections might be made for coincidence losses in Bi-214 using the type of
approach described, for example,  in "Gamma Ray and X-ray Spectrometry with
Semiconductor Detectors" (Debertin and Helmer, Pub by North-Holland ISBN 0
444 871071) but it is too much work for my taste  - better to avoid a
problem than deal with one.

Paul Frame
Professional Training Programs
ORAU
framep@orau.gov
http://www.orau.gov/ptp/ptp.htm
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