[ RadSafe ] Fe-55 on LSC

[Michael Bohan]

Hello RadSafers,

I used to leak test an Fe-55 source that was used to QA an x-ray 
microscope.  The NRC, in the licensing process, insisted that I had to 
demonstrate my LSC efficiency for the wipe tests, so I also had to 
purchase a liquid Fe-55 standard ampoule from what was then Isotope 
Products Lab, which is now Eckert & Ziegler Isotope Products.  From 
that I made a LSC standard with a contained activity of 0.211 uCi.

Using the standard tritium LSC window, I was able to get an efficiency 
of around 14 - 20%, over the years I performed the tests.  However, if 
you are going to do this and you need to demonstrate the results to 
regulators, you will have to manufacture your own standard or have some 
one make it for you.  You'll need to make sure they use the same type 
of vial and scintillant that you plan to use.  The energy is so low 
that quenching and other factors can easily affect your efficiency.

Regards,

Mike Bohan, RSO
Yale-New Haven Hospital
Radiological Physics
20 York St. - WWW 204
New Haven, CT 06510
Tele: (203) 688-2950
Fax: (203) 688-8682
Email: mike.bohan at yale.edu

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