Re: Efficiency Determination

[Wes Van Pelt <VanPeltW@mail.IDT.net>]

Judd Sills wrote:
snip.....
> Electroplated sources are good for this type of situation.  FYI, the Ludlum
> reported efficiency specifications (2 Pi) for this beta-gamma pancake probe are:
> C-14    10%
> Sr-90/Y-90      45%
> Tc-99   38%
> P-32    65%
> Pu-239  30%
> 
> The 4 Pi geometries are one half of the above values.
> 
> 

Dear Radsafers,

Judd makes some very good points.  Thanks.

Looking at the above efficiencies, there is an apparent inconsistency.
Sr-Y-90 should have a substantially higher counting efficiency than P-32
since Sr-Y-90 has 2 betas per decay, one of which (2.27 Mev) is quite a
bit higher energy than that of P-32, and the other (0.546 MeV) ain't too
shabby either.

Are Ludlum's specs just wrong here, or am I missing something?

Wes
-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                   KF2LG
President, Van Pelt Assoc., Inc.      vanpeltw@mail.idt.net
Consulting in radiological health and safety.
"TIME, its what keeps everything from happening at once."