Re: X rays, high altitude, and floppy disks

["H.B. Knowles" <hbknowls@ix.netcom.com>]

At 13:46 12/21/1999 Tuesday-0600, you wrote:
>Hello All;
>
>I recently got a question from a software distributor regarding
>radiation effects on the software they distribute overseas (out of the
>US).  Their observation is that approximately 1 in 5 floppy diskettes
>are damaged while being shipped overseas; this problem does not occur in
>domestic shipments.  They assumed that the damage is caused by x rays
>used by customs inspection.  The damage is usually on the diskettes
>closest to the exterior of the package, and they say that wrapping their
>disks in aluminum foil eliminates the problem.
>
>Based on threads regarding radiation at high altitudes, my guess is that
>the long flight at high altitude might be a more likely culprit.
>
>Can anyone confirm of correct me?
>
>Thanks in advance,
>
>Paul R. Steinmeyer
>Radiation Safety Associates, Inc.
>RSA Laboratories, Inc.
>mailto:prstein@radpro.com
>************************************************************************
>The RADSAFE Frequently Asked Questions list, archives and subscription
>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
 
Mr. Steinmeyer:

Like others who have responded, the presence of Al foil does not appear to me
to be very effective in stopping x-rays (except at the lower energies, where
there might be some effect). But as to upper altitude radiation, there is no
reason to expect any mitigation from any reasonable type of shielding.  Th
30,000  ft radiation field is (VERY roughly) 0.5 mrem/hr at 45degrees N
magnetic latitude of which about 40-45% is caused by neutrons. THese, in
particular would quite possibly cause misalignment of magnetic domains by
collision, and would (unlike most ionizing radiations) be able to bcause some
disruption. So also would  accompaying quasi-equillibrium spectra of fast
protons, and possibly pions. But these are certainly not eliminated by a little
Al foil. Look to electromagnetic fields as the cause, possibly in the
package-handling equipment.
H.B. Knowles, PhD, Physics Consulting
4030 Hillcrest Rd, El Sobrante, CA 94803
Phone (510)758-5449
Fax (510) 758-5508
hbknowls@ix.netcom.com (until 1/31/00)
hbknowles@hbknowles.com (new)
<www.hbknowles.com>
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html