Re[2]: Zinc-65 Intake??? -Reply

[FRAMEP@ORAU.GOV]

Dick:

I am sure you have taken this into account but for the sake of
general interest let me mention an experience I had with Zn-65. I was
on a tour of a nuclear power plant when I set off a portal alarm. The
HPs confiscated the source of the radiation: my camera. Of course it
was the thorium-coated lens that set of the alarm but the gamma spec
program they used in the analysis was only set up for activation and
fission products. Their id was Zn-65 (they grumbled about me tracking
contamination from Oak Ridge into their nice clean plant). 

A problem with this nuclide is that it has a reasonably high energy
gamma. This means the gamma from any Zn-65 present in the background 
might penetrate the detector shield. Its relatively short half life
means that the amount seen in the background can fluctuate quite a
bit. As such, the background spectrum  stripped out prior to analysis
needs to be obtained recently. 

Oddly enough, some old gamma catalogs listed the Zn-65 gamma at 1119
keV, right on top of the bismuth line. 

By the way, I got my camera out of the plant: I persuaded management
to overrule the HPs.


Paul Frame