Efficiency Determination

[Julia Sober <T80JCS1@WPO.CSO.NIU.EDU>]

Dear Radsafers,

I have recently obtained a Ludlum Model 3/44-9 and am in the process of
performing efficiency calculations for various isotopes in use at my
facility, namely P-32, S-35, I-125, and C-14.  In determining efficiency, I
plan to take a measured amount of each isotope, place it on a disc
smear, determine the count rate, and perform the necessary
calculations.

Yesterday the above method gave me a 30.6% efficiency for P-32.

I would like to know if this is within the expected range for this
instrument and if this is an efficient (so to speak) method for determining
efficiency.

I would also appreciate a list of expected efficiency ranges for the
Model 3/44-9 for the isotopes I have listed if anyone is using similar
instrumentation and has these numbers handy.

In Anticipation, 
Julia Sober
Acting RSO
Northern Illinois University
DeKalb, IL 60115

jsober@niu.edu
Phone (815) 753-1093
Fax (815) 753-0461