Re: A couple off-the-wall (unrelated) questions

[jgbarnes@ix.netcom.com (JAMES BARNES)]

To Jim Herrold;

>#1.  What recommendations do other research institutions follow for monitoring
>technicians in x-ray diffraction labs.

We now have all shielded units.  Used to have an open air GE model from about 
1955.  We have generally used whole body film or TLDs as an *indicator* of an 
event.  In very specific situations, we have used finger rings, but not routinely 
(it was felt that the narrow beam and "wobbly hand" effect didn't really result 
in any useful data that we didn't already see on the whole body badge).
>
>#2.  Can pancake geiger detectors be set off by high electromagnetic fields?
>
My experience is that yes it can, but not consistently.  Just about any GM probe 
will "pulse" in sync with an RF field (found this out when we were running a 
linac on an FEL).  I have also noted some type of odd "spike" when a probe is 
suddenly shifted in position when frisking metallic objects (I've never heard an 
explanation for that, but suspect some kind of electromagnetic thing).  Magnetic 
fields may also affect the probe's behavior.

I've seen friskers misbehave when someone was welding nearby; suggests EMF 
interference.

By the same token, make sure that the probe is still intact.  A broken probe 
window will cause the instrument to fail high in many cases.  Also they have a 
tendency to get internal shorts in the handle and shielded casing.  Might want to 
check that out also.


Jim Barnes, CHP
Rockwell Aerospace; Rocketdyne Division
Radiation Safety Officer