Rad Reading on mag storage drums

[John C White <ohjcw@utxdp.dp.utexas.edu>]

I used to be a Nuclear Effects engineer in the defense industry.  While evaluat
ing a large capacity hard drive, I happened to have a G-M detector near the
drive, and noticed readings.  Curious, I moved the detector around the unit,
and found the readings varied from 0.5 mR-0.75 mR.  I used a shield of mu-metal
to shield the detector from the drum, and the readings dropped off.  At the
time, I thought the magnetic fields from the drum were inducing readings in
the detector or the cabling.  Perhaps this may be an explanation for your
phenomena.
John C. White, RSO
The University of Texas at Austin