Re: Efficiency Determination

[Peter.Darnell%EM@em.doe.gov]

Message authorized by:
    : T80JCS1@WPO.CSO.NIU.EDU_at_INTERNET at X400PO
     From my experience, for P32 an efficiency of 30 to 40% is within the 
     realm of possibilities.  You should realize that efficiencies will 
     vary with isotope and even probe to probe.  Additionally, it would be 
     much easier on you if you bought an NIST traceable source for your 
     calibrations.  This gives you a good QA record without having to make 
     your own sources.  There is less chance of error and less for auditors 
     (like the NRC) to question.
     
     Pete Darnell
     Radiological Protection Manager
     DOE-Fernald


______________________________ Reply Separator 
_________________________________
Subject: Efficiency Determination
Author:  radsafe@romulus.ehs.uiuc.edu_at_INTERNET at X400PO
Date:    11/26/96 12:25 PM


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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