What is it ?

[Gerald Laurence <Gerald.Laurence@aduchem.com.au>]

Last year the group was very helpful when I had a question about dose
measurements for high altitude fliers. I hope you can help my current query.
We have found in a clean-up of a lab in the Geology department, three
gadgets which a departmental technician claimed were "very slightly
radioactive". So they are - a few count per sec above background. BUT when
I investigated, there is a spring-loaded shutter which when opened shows as
10s of microSieverts/hr (1mrem/hr) or more.
Gamma spectra shows it to be Cs-137 and a VERY rough calculation suggests
the most active of the three may have about 1 microCurie (40 kBq) of
Cs-137. The oldest inhabitant of the department doesn't know what they are,
and there are no records of the sources anywhere.
I have photos of both sides of the thing at

http://www.adelaide.edu.au/HR/OH&S/georad.htm

I hope you can read the pictures - I forgot a scale, but each is about 10
cm across and they are made to fit (slides, locking handles etc) in some
instrument.
The pics show each side; the yellow painted blob on the silver shutter in
Photo 1 covers the source; the source seems to be held in by the spring
circlip shown in Photo 2.
Any suggestions ?

Gerald 
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