Re: specific activity

[Dave Derenzo <dave@uic.edu>]

See Herman Cember's book, third edition, Equation 4.31 on p.95.

S.A. = (226 x 1600)/(Atomic Weight x Half Life in Years)

226 and 1600 refer to the atomic weight and half-life in years of 
radium-226.  Simply plug the atomic weight and half-life (in years) of the 
radionuclide of interest into the equation.  This will yield the specific 
activity in Ci/g.

He provides examples for C-14 and S-35:

C-14
S.A. = (226 x 1600)/(14 x 5730) = 4.5 Ci/g
(The book gives 4.6 as the answer, but the above answer is correct)

S-35 (I modified this example slightly)
S.A. = (226 x 1600)/(35 x 87.51 d /365.25 d/y) = 4.31E4 Ci/g = 0.04 uCi/g

If you are interested in specific concentration, divide the activity by the 
volume of the solution.

Dave Derenzo

At 12:49 PM 06/14/2000 -0500, you wrote:
>how does one go about determining the specific activity of something in
>uCi/g ?
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Dave Derenzo, RSO (dave@uic.edu)
UIC Radiation Safety Section, M/C 932
Phones: Voice (312) 996-1177  Fax: (312) 996-8776

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