🚀 go-pugleaf

Duncan,

X-rays at the exposure levels that you will encounter in airport
screening devices have no effect whatsoever on the magnetic properties
of magnetic media.

Regards.

Bill

BILL R. King, PE
Data Recovery International
2621 Brookridge Drive
Hurst, TX, 76054  USA

Tel 817-281-8901
Fax 817-656-0079

http://www.datarecover.com
brking@datarecover.com 




Duncan W Kennedy wrote:
> 
> I have to take 250 floppies by internal air tomorrow.  The contain
> important presentation material.
> 
> Anyone tell me, please if they are safe from x-rays at (UK) airports?
> 
> --
> Duncan W Kennedy
> Otterson Business Graphics
> http://www.otterson.demon.co.uk/

In <dLKK+CAAYyV1EwnZ@otterson.demon.co.uk>, Duncan W Kennedy wrote:

>I have to take 250 floppies by internal air tomorrow.  The contain
>important presentation material.
>
>Anyone tell me, please if they are safe from x-rays at (UK) airports?

Yes, what makes you think they wouldn't be?

Most packs of floppies come with handling instructions. The main things to avoid
are magnets!
-- 
Bob Cousins, Software Engineer.
Home page at http://www.lintilla.demon.co.uk/

Duncan W Kennedy wrote:

> I have to take 250 floppies by internal air tomorrow. 
> Are they safe from x-rays at (UK) airports?

X-rays themselves won't damage magnetic media. Watch for close 
magnetic fields (e.g, don't put them in a bag on the floor of an 
electric train with motors possibly under the floor).

Magnetotstatic fields fall off very rapidly with distance, so a few 
centimeters of separation from the field make a difference.

As the X-ray machines may generate magnetic fieldes, I'd put the 
discs in the MIDDLE of a bag and let them go through.

You could always back up the presentation on a writeable CD. In fact, 
it's got to be better than 250 floppies.

Or a cheap, old parallel port tape backup with 250MB capacity.

Best wishes,
-- 
Michael Salem

On Mon, 11 May 1998 17:23:28 +0100, Duncan W Kennedy
<duncank@otterson.demon.co.uk> wrote:

>I have to take 250 floppies by internal air tomorrow.  The contain
>important presentation material.
>
>Anyone tell me, please if they are safe from x-rays at (UK) airports?

    Normal airport X-ray machines won't harm them.  If you want to be
absolutely sure I have always found that handing such material in an
open box to the search officers was always OK.

   Regards,
        Harry.

In <35572984.7A6A@datarecover.com>, Bill R. King wrote:

>X-rays at the exposure levels that you will encounter in airport
>screening devices have no effect whatsoever on the magnetic properties
>of magnetic media.

For interest, what level of X-rays would be required to cause a problem, and
where could that level be found?

-- 
Bob Cousins, Software Engineer.
Home page at http://www.lintilla.demon.co.uk/

I am referring to airport x-rays, not magnetic felds from magnets. 
Magnets are a different discussion.

Bill


Bob Cousins wrote:
> 
> In <dLKK+CAAYyV1EwnZ@otterson.demon.co.uk>, Duncan W Kennedy wrote:
> 
> >I have to take 250 floppies by internal air tomorrow.  The contain
> >important presentation material.
> >
> >Anyone tell me, please if they are safe from x-rays at (UK) airports?
> 
> Yes, what makes you think they wouldn't be?
> 
> Most packs of floppies come with handling instructions. The main things to avoid
> are magnets!
> --
> Bob Cousins, Software Engineer.
> Home page at http://www.lintilla.demon.co.uk/

The x-ray exposure would probably have to be sufficient to cause
degraduation of the polymers and lubricants in the coatings and
substrate. As I recall, the dose to do this is in the megarad range.

Quote from NBS Special Publication 500-001, "Care and Handling of
Computer Magnetic Storage Media" by S.B. Geller:

"Recorded magnetic media are often subjected to to x-ray energy in
airport surveillance systems. Tests were performed with various recorded
magnetic media in the NBS Radiation Physics Laboratory. The media were
subjected to extremely high (lethal) x-ray dosages. No data loses were
incurred. Recorded media were also subjected to normal x-ray inspection
at two airports with no resultant loss in data"

Hope this helps.

Bill

BILL R. King, PE
Data Recovery International
2621 Brookridge Drive
Hurst, TX, 76054  USA

Tel 817-281-8901
Fax 817-656-0079

http://www.datarecover.com
brking@datarecover.com 




Bob Cousins wrote:
> 
> In <35572984.7A6A@datarecover.com>, Bill R. King wrote:
> 
> >X-rays at the exposure levels that you will encounter in airport
> >screening devices have no effect whatsoever on the magnetic properties
> >of magnetic media.
> 
> For interest, what level of X-rays would be required to cause a problem, and
> where could that level be found?
> 
> --
> Bob Cousins, Software Engineer.
> Home page at http://www.lintilla.demon.co.uk/

Michael,

The "old parallel port tape backup" probably has tape that has a
coercivity of about 300 Oe as compared to more than 600 Oe for a floppy
disk. That "old" tape will be much more susceptible to stray magnetic
fields than will a floppy disk. 

However, all are more tolerant of magnetic fields than you might expect.
As a experiment, I suggest that you try to erase or corrupt the data on
a duplicate floppy disk by exposing the disk to a magnet held at various
distances from the disk surface. I believe that you will be surprised at
the results.

Regards

Bill

BILL R. King, PE
Data Recovery International
2621 Brookridge Drive
Hurst, TX, 76054  USA

Tel 817-281-8901
Fax 817-656-0079

http://www.datarecover.com
brking@datarecover.com

Michael Salem wrote:
> 
> Duncan W Kennedy wrote:
> 
> > I have to take 250 floppies by internal air tomorrow.
> > Are they safe from x-rays at (UK) airports?
> 
> X-rays themselves won't damage magnetic media. Watch for close
> magnetic fields (e.g, don't put them in a bag on the floor of an
> electric train with motors possibly under the floor).
> 
> Magnetotstatic fields fall off very rapidly with distance, so a few
> centimeters of separation from the field make a difference.
> 
> As the X-ray machines may generate magnetic fieldes, I'd put the
> discs in the MIDDLE of a bag and let them go through.
> 
> You could always back up the presentation on a writeable CD. In fact,
> it's got to be better than 250 floppies.
> 
> Or a cheap, old parallel port tape backup with 250MB capacity.
> 
> Best wishes,
> --
> Michael Salem

Bill R. King <brking@datarecover.com> wrote in article
<3557A07B.2F68@datarecover.com>...
> I am referring to airport x-rays, not magnetic felds from magnets. 
> Magnets are a different discussion.

But the X-ray generator / scanner / any part of the whole get-up may
involve magnetism.

TB

In <3557A571.7E0F@datarecover.com>, Bill R. King wrote:

>"Recorded magnetic media are often subjected to to x-ray energy in
>airport surveillance systems. Tests were performed with various recorded
>magnetic media in the NBS Radiation Physics Laboratory. The media were
>subjected to extremely high (lethal) x-ray dosages. No data loses were
>incurred. Recorded media were also subjected to normal x-ray inspection
>at two airports with no resultant loss in data"
>
>Hope this helps.

Yep, I think that nails it. If you survive the scanner, so does your data :-)

Generally, are any items of computer equipment at risk from airport scanners or
other sources of radiation? I think only photographic film is at risk, and then
only slightly.

The main risks to me seem to be all mechanical damage.
-- 
Bob Cousins, Software Engineer.
Home page at http://www.lintilla.demon.co.uk/

Bill R. King wrote in response to a posting of mine:

> Michael,
> 
> The "old parallel port tape backup" probably has tape that has a
> coercivity of about 300 Oe as compared to more than 600 Oe for a floppy
> disk. That "old" tape will be much more susceptible to stray magnetic
> fields than will a floppy disk. 
> 
> However, all are more tolerant of magnetic fields than you might expect.
> As a experiment, I suggest that you try to erase or corrupt the data on
> a duplicate floppy disk by exposing the disk to a magnet held at various
> distances from the disk surface. I believe that you will be surprised at
> the results.

I know; I suggested the use of tape because of its large capacity, 
not as a solution to the magnetic field problem. The inverse cube law
of magnetostatic fields makes them not a serious problem; a few 
centimeters of distance make all the difference.

I wrote a book on tape recording and home computers a few years ago 
(when it was relevant!) in which these topics were covered.

Best wishes,
-- 
Michael Salem

Bob Cousins wrote:

> >X-rays at the exposure levels that you will encounter in airport
> >screening devices have no effect whatsoever on the magnetic properties
> >of magnetic media.
> 
> For interest, what level of X-rays would be required to cause a problem, 

A level sufficient to physically destroy the magnetic coating or the 
substrate.

> and where could that level be found?

In the vicinity of a supernova. Maybe a military X-ray laser (if they 
exist).

HTH,
-- 
Michael Salem

In article <35782e3e.2088195736@news.demon.co.uk>,
Harry Broomhall <haeb@demon.net> wrote:
>     Normal airport X-ray machines won't harm them.  If you want to be
> absolutely sure I have always found that handing such material in an
> open box to the search officers was always OK.

Sometime back in the 80s, Byte Magazine did an objective test. They
took about 100 800K floppies and 100 360K floppies, wrote a test
pattern on them, and subjected them to standard checked and unchecked
baggage X-ray machines.

They found that the failure rate (where "failure" is at least 1 wrong
bit on the entire disk) among the zapped disks was substantially
higher, both for the standard X-ray and the unchecked bags X-ray. I
don't remember the exact number, but I think it was around 7%,
compared to around 1% for the control group.

However, since the disks were simply carried or checked by Byte
staffers on routine flights, they couldn't rule out environmental or
magnetic contamination due to something other than X-rays.

Rick R.

It depends on how friendly the airport search officers are. Go to
JFK and try giving the disks to the officiers and they'll bite your
head off and shit down your neck and throw your disk through the
Xray machine anyway. In other countries, the officiers are much
nicer. Except if you're Arabic looking, in which case you'll get
no end of hassle. These are what I've observed personally while
travelling.

ken

In article <6ja30v$64s$1@joe.rice.edu>,
  rickr@is.rice.edu wrote:
>
> In article <35782e3e.2088195736@news.demon.co.uk>,
> Harry Broomhall <haeb@demon.net> wrote:
> >     Normal airport X-ray machines won't harm them.  If you want to be
> > absolutely sure I have always found that handing such material in an
> > open box to the search officers was always OK.
>

-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/   Now offering spam-free web-based newsreading

It would take an unfeasibly high x-ray dose to damage a floppy disk.
However...

X-ray machines tend also to contain large focusing magnets or
electromagnetic coils of one sort or another, and these are a more
significant hazard to a disk. Make sure you don't pack disks near the outer
surface of a bag where they could get very close to the edges of the X-ray
tunnel. As long as they stay away from the edge, they are also very unlikely
to encounter any significant magnetic fields.

--
Alex Gray
Editor Corel User magazine
editor@coreluser.com
http://www.enterprise.net/cvu
Duncan W Kennedy wrote in message ...
>I have to take 250 floppies by internal air tomorrow.  The contain
>important presentation material.
>
>Anyone tell me, please if they are safe from x-rays at (UK) airports?
>
>--
>Duncan W Kennedy
>Otterson Business Graphics
>http://www.otterson.demon.co.uk/
>

In article <6jcceu$fhs@bbcnews.rd.bbc.co.uk>
           alex@oupc.bbc.co.uk "Alex Gray" writes:

Having a pragmatic nature, I don't really care what complex
physics, etc say - I simply know that on my travels I regularly
take floppies with me and I have NEVER had any problems.

I know they are being x-rayed, I usually carry them in my hand
luggage and that is ALWAYS passed through an x-ray machine, I
even see the contents on the screen.

HTH
Ernest
-- 
ernest     at Noel Systems, near Kingston-upon-Thames (UK)
           (if replying by email, use postmaster)