Re: Leak Testing of Radiography sources

["Wesley M. Dunn" <WDUNN@brc1.tdh.texas.gov>]

> Date: Wed, 12 Oct 94 07:35:00 -0500
> From: Ninni Jacob <njacob@gsosun1.gso.uri.edu>
> Subject: Leak Testing of Radiography sources
>
> Do any of you have experience with leak testing of radiography sources,
> specifically, Iridium and depleted uranium(in the camera)? Apparently it
> is wiped with a Q-tip. How do you count the q-tip, other than by liquid
> scintillation? Have you tried dissolving the radionuclide out of the q-tip?
> Any hints would be helpful.
> Thanks
>

Since you are looking for the gamma (for Ir-192), LSC is not normally
a good approach.  I'd use a NaI rig (1*1 will do) in a fixed
geometry.  Place the q-tip on the planchet (w/ a filter paper in
between) and count for a set time.  Geometry is conservative, since
most button sources will be "further" from the detector, since the q-
tip has a larger thickness.  Self-shielding is negligible for Gamma.
This should also find any gammas off the DU (and is much "cleaner"
than using LSC, unless you have a DU checksource in cocktail.  LSC
will see all the noise, but calibration is a bear).

Wes Dunn