Airport X-Rays
P. J. Holsberg
Will airport X-rays cause any damage to portable computers and/or their
components? How about damage to 3.5" floppy disks?
Thanks.
Steve McKinty - Sun ICNC
The X-rays themselves won't do any damage, unless you're carrying something
like 1000ASA photographic film, but they use pretty hefty electromagnets
to focus the beam, so I never trust floppies or tapes in them, just in case.
Steve
Harald Ljoen FBA
I once found it convenient to "unformat" 5.25" floppies with a ferrite magnet
rod originally designed to demagnetize a large color CRT. 3.5" floppies are
virtually insensitive to this treatment. I haven't yet found a magnet strong
enough to destroy the data on a 3.5" disk, so I suspect there's
a very efficient magnetic shielding in the material in the casing.
--
***** h...@hal.nta.no (Harald Ljo"en) expressing his private opinions ******
Klaus Burkert
>Hello all. We just recently received a couple of clones that came
>with Diamond Speedstar ET4000 cards. The manufacturer claims that
>these are Hicolor cards, but we have so far been unable to verify
>this.
>
>My question is: Is there anyway to determine the presence of a HiColor
>RAMDAC through a software utility (I've tried viewing some 24-bit
>Targa images via a GIF viewer with a hicolor driver loaded, but the
>results have been inconclusive so far).
There's a BIOS call on biosses with HiColor extensions reporting the type of
DAC installed but I don't have it handy. From memory I think it was
AX = 10F1h, INT 10h and tghe result in BL with:
00h : normal DAC
01h : Sierra-DAC
other : not defined yet.
>Also, I looked at the DAC itself. It has a diamond-shaped logo, and
>the part number is SC11486CV. Can anyone tell me what kind of chip
>that is?
The logo is Sierra's logo and the 11486 is a HiColor-DAC!
Of course HiColor means 15bit-colordepth (5 bit per gun) and NOT
truecolor which is 24 bit or 8 bit per gun giving 16M colors.
Ciao, Klaus.
-----------------------------------------------------------
Klaus Burkert email: burk...@kirk.fmi.uni-passau.de
Brandweg 11 voice: +49-851/83993 (only pm please)
D-W-8390 Passau / Federal Republic of Germany
Meir I Green
No, there isn't. It is because the higher the media density, the smaller
the required particle size, and the stronger the required coercivity. In
other words, the 3.5 inch drives have stronger magnets because the disks
require it. And the disks are, therefore, much less susceptible to weak
magnetic fields!
* * * * * ================= Internet address is m...@cunixb.cc.columbia.edu
* * * * * * = Meir I. Green = for short, mail to m...@columbia.edu
* * * * * ================= UUCP Bang! columbia.edu!mig
* * * * * * ================= Amateur Packet Radio N2...@W2XO.PA.USA.NOAM
Jimmy Dalin
carry-on bag. It has been X-rayed 30-50 times in the past few years. The
floppy is still perfectly readable.
--
Jim Dalin "No Salga Afuera"
AT&T N.Y.C.T.A.
ATTMail id: !jdalin
Compuserve: 72260,1573
PauL M SchwartZ
One thing to be aware of is that most, if not all, metal detector
hardware in use at airports utilize a strong magnetic field to check if you're
carrying any large chunks of metal. Where as the focus beam in the "X-ray"
machine is on par with that of a large computer monitor. I believe it is in
fact better to pass your computer stuff through the X-ray machine rather than
to hand it around to a guard. The x-ray machine's (wow, typed Xray differently
all 3 (guess that's 4 now) times) shielding that keeps the guards from getting
to high a dose of radiation will keep your computer stuff from getting to high
a dose of magnetism.
PauL M SchwartZ | Follow men's eyes as they look to the skys
Future site of .sig virus | the shifting shafts of shining
v206...@ubvms.BitNet | weave the fabric of their dreams.
p...@acsu.buffalo.edu | - RUSH -
Jason O'Rourke
a strong magnetic field, right where the guard would hand check your pc. While
even there the risk is low, it is much greater than subjecting it to xrays.
Jason O'Rourke
Ps: make backups
Gabe M Wiener
>
> Where as the focus beam in the "X-ray"
>machine is on par with that of a large computer monitor.
That may be so, but the bigger danger comes not from the x-rays, but
rather from the magnetic fields generated by the motor used to move
they conveyor belt.
> I believe it is in
>fact better to pass your computer stuff through the X-ray machine rather than
>to hand it around to a guard.
If you hand it around to a guard, it neither gets put through the x-ray
machine nor through the metal detector.
Most airports will gladly hand-check computer hardware, though if it's
a laptop you're carrying, they'll ask you to turn it on.
--
Gabe Wiener - Columbia Univ. "This 'telephone' has too many shortcomings
gm...@cunixa.cc.columbia.edu to be seriously considered as a means of
N2GPZ in ham radio circles communication. The device is inherently of
72355,1226 on CI$ no value to us." -Western Union memo, 1877
Bill Endter RCS
|>
|> One thing to be aware of is that most, if not all, metal detector
|> hardware in use at airports utilize a strong magnetic field to check if you're
|> carrying any large chunks of metal. Where as the focus beam in the "X-ray"
|> machine is on par with that of a large computer monitor. I believe it is in
|> fact better to pass your computer stuff through the X-ray machine rather than
|> to hand it around to a guard.
If the magnetic field was really strong wouldn't it erase your credit cards? I have never had any credit cards erased by going through the metal detectors. Has anyone heard of this happening?
Bill
Frank Tompkins
electromagnets to focus the (x-ray) beam"???
X-rays are energetic photons, and as such, are unaffected by magnetic fields.
I guess you could use a magnetic field to focus and manipulate the electron
beam which, when accelerated into a target (usually tungsten), produces x-rays,
but in the half dozen x-ray machines I've examined and taken apart, I've never
seen this done. What is often done is to encase the x-ray tube, high
voltage power and filament transformers in a pressurized housing filled with
dry nitrogen or argon to reduce the corona and arc over problems. The
proximity of the transformer (and it's magnetic leakage) to the x-ray source
is probably what damages magnetically sensitive materials. I believe the
fear that x-rays can damage magnetic material dates back to the late 60's and
early 70's when airport x-ray machines were adapted from other x-ray machines
(in the panic to stop hijacking) and the magnetic media was audio tapes, which
were recorded at a lower flux density than today's data storage media.
I've never had a diskette (5.25 of 3.5) damaged at a U.S. airport. Foreign
airports could be another story. Also, the lead bags offered at photo shops
do nothing to shield their contents from magnetic fields (just x-rays).
Someone posted that the magnetic field from the conveyer drive motor may be
a problem, I dono, could be - maybe I've been lucky! Good luck, and long
live your magnetic fields!
- Frank
*************************************************************************
Frank Tompkins "The strength of the constitution lies directly in
University of Akron the determination of each citizen to defend it"
Akron, Ohio 44325-3501 A. Einstein
Bob Billson
]I once found it convenient to "unformat" 5.25" floppies with a ferrite magnet
]rod originally designed to demagnetize a large color CRT. 3.5" floppies are
]virtually insensitive to this treatment. I haven't yet found a magnet strong
]enough to destroy the data on a 3.5" disk, so I suspect there's
]a very efficient magnetic shielding in the material in the casing.
I have used a large speaker magnet to quickly erase 5.25 and 3.5 inch floppies.
Works quite nicely. The is no magnetic shielding in the material of a 3.5 inch
floppy case, just plain old plastic.
Bob
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Bob Billson, KC2WZ | internet: b...@kc2wz.bubble.org
| kc...@amsat.org
$nail: 21 Bates Way, Westfield, NJ 07090 | uucp: ...!uunet!kc2wz!bob
C code. C code run. Run code run...<please!>
Pete Holsberg
=I have used a large speaker magnet to quickly erase 5.25 and 3.5 inch floppies.
=Works quite nicely. The is no magnetic shielding in the material of a 3.5 inch
=floppy case, just plain old plastic.
Does it matter what music is playing through the speaker?? ;-)/2
Quentin Barnes
Don't worry. Metal detectors use electro-magnetic fields (radio waves)
to detect metal, not magnetic fields.
> Bill
>
--
Quentin Barnes
qba...@urbana.mcd.mot.com | ..!uiucuxc!udc!qbarnes
Hamish Moffatt
>The X-rays themselves won't do any damage, unless you're carrying something
>like 1000ASA photographic film, but they use pretty hefty electromagnets
>to focus the beam, so I never trust floppies or tapes in them, just in case.
Someone once told me that floppy disks have huge ASA speeds - much bigger
than 1000ASA. No idea if this is true though.... (if true the X-rays could do
damage too..)
Hamish
--
Hamish Moffatt, ham...@cloud.pub.uu.oz.au -and- ham...@werple.pub.uu.oz.au.
Note new path to cloud: ...!eyrie.img.com.au!cloud Thank you. :-)
Ted Cantrall
*>>like 1000ASA photographic film, but they use pretty hefty electromagnets
*>>to focus the beam, so I never trust floppies or tapes in them, just in case.
*>
*==========================================================================
Someone who travels often should do us all a favor and experiment. Pack
360K, 1.2M and 1.4M disks with data (one big ZIP file, perhaps) and put
them in the luggage that will be X-rayed. Trying to unZIP the file will
reveal if any of the data has been corrupted. If several people do this
in several airports (a variety of X-Ray equipment) and post the results,
we'll all know for sure.
-ted-
-------------------------------------------------------------------------------
t...@helios.ucsc.edu |"He has showed you, O man, what is good; and what does the
W (408)459-2110 |Lord require of you but to do justice and to love kindness
H (408)423-2444 |and to walk humbly with your God?" Micah 6:8 (RSV)
David Salamon
>The X-rays themselves won't do any damage, unless you're carrying something
>like 1000ASA photographic film, but they use pretty hefty electromagnets
>to focus the beam, so I never trust floppies or tapes in them, just in case.
Just a physics point here, but electromagnets will not focus ANY
electromagnetic wave, including X-rays. Remember superposition of fields?
People have been trying to focus X-rays for many years without much success.
Virtually all X-ray machines just use incoherent, unfocussed X-rays.
If there are magnets in those X-ray machines, they are most likely in the
motors running the conveyer belt.
David
--------------------------------------------------------------
David Salamon Physics Graduate Student (Slave)
d-sa...@uiuc.edu University of Illinois
--------------------------------------------------------------
David Lee
>smck...@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:
.>The X-rays themselves won't do any damage, unless you're carrying something
.>like 1000ASA photographic film, but they use pretty hefty electromagnets
.>to focus the beam, so I never trust floppies or tapes in them, just in case.
>Just a physics point here, but electromagnets will not focus ANY
>electromagnetic wave, including X-rays. Remember superposition of fields?
>People have been trying to focus X-rays for many years without much success.
>Virtually all X-ray machines just use incoherent, unfocussed X-rays.
>If there are magnets in those X-ray machines, they are most likely in the
>motors running the conveyer belt.
I think it would be smart to avoid any magnetic fields, either generated
by permament magnets or electromagnets,.i.e. motors,..etc. Data on
floppy or hard disk is of a magnetic nature; and any magnetic field
can, erase if strong enough, or distort so that the pc cannot recover
the data.. PC users have been cautioned constantly about leaving floppy
disk by telephones and on top of monitors.. It might not happen, but it
could.. So, why take the risk??? It's amazing where you can find magnetic
fields in an office or home environment!!!
Fogging of photographic film is another matter and caused by high energy
particles (X-rays,..etc.) and not by magnetic fields..
.
.
.
..
Ron Snyder
Someone who travels often should do us all a favor and experiment. Pack
360K, 1.2M and 1.4M disks with data (one big ZIP file, perhaps) and put
them in the luggage that will be X-rayed. Trying to unZIP the file will
reveal if any of the data has been corrupted. If several people do this
in several airports (a variety of X-Ray equipment) and post the results,
we'll all know for sure.
I'll do this, but you'll have to wait until the end of September to find
out the results. :)
--
Ron Snyder <r...@bert.cs.byu.edu> <snyd...@coned1.byu.edu>
****************************************************************
Ralph Becker-Szendy
>I think it would be smart to avoid any magnetic fields, either generated
>by permament magnets or electromagnets,.i.e. motors,..etc. Data on
>floppy or hard disk is of a magnetic nature; and any magnetic field
>can, erase if strong enough, or distort so that the pc cannot recover
>the data.. PC users have been cautioned constantly about leaving floppy
>disk by telephones and on top of monitors.. It might not happen, but it
>could.. So, why take the risk??? It's amazing where you can find magnetic
>fields in an office or home environment!!!
Good idea. First step is to avoid the earth. Around the countryside,
the greatest danger is from the earth's magnetic field (which is
around 1/3 gauss, if my memory serves me right). So off to space we go
(I knew there was a good reason to build the space station) :-) If you
want to be extra-careful, please remember that the planet Jupiter has
a substantial magnetic field (strong enough to be measureable on
earth, which measurement for a while set the best limit on the mass of
the photon, by the way).
Now serious. Could someone present some more quantitative information
about what strength of magnetic field it takes to damage a floppy of a
certain density (8" SSSD will probably react very different from a ED
4MB 3.5" floppy)? How about tapes ? I have successfully bulk-erased
6250 bpi 9-track tapes, but I hear that 8mm tapes are just about
impossible to bulk-erase. What magnetic field does it take? Facts
please; not urban legends or generic warnings.
And while we are asking for facts (which are a rare find on this
newsgroup): How about EPROMs and similar stored-charge memory devices?
After all, EPROMs are erased by UV, do they resist the airport X-ray
machine? I'd guess that the X-rays are heavily attenuated by the case
of the EPROM (the top of which is transparent to UV light but not to
X-rays), but is there real danger to EPROMs ?
--
Ralph Becker-Szendy RA...@SLACVM.SLAC.STANFORD.EDU
Stanford Linear Accelerator Center RA...@SLACVM.BITNET
M.S. 95, P.O. Box 4349, Stanford, CA 94309 (415)926-2701
My opinion. This is not SLAC, Stanford U, or the US DoE speaking. Just me.
amco...@ulkyvx.louisville.edu
>
> Someone who travels often should do us all a favor and experiment. Pack
> 360K, 1.2M and 1.4M disks with data (one big ZIP file, perhaps) and put
> them in the luggage that will be X-rayed. Trying to unZIP the file will
> reveal if any of the data has been corrupted. If several people do this
> in several airports (a variety of X-Ray equipment) and post the results,
> we'll all know for sure.
>
Three years ago I subjected various types of floppies (5.25, 5.25 HD, 3.5, 3.5
HD) to as much as 1.5 Gy of x rays. File and media verification showed no
errors and the disks appeared fine. I didn't think anything would happen but I
did this to satisfy colleagues who had their doubts. As previous posters have
stated, it is the magnetic fields associated with the HV transfromers used in
radiographic units which have the most potential for causing damage to magnetic
media. An x-ray flux would have to be quite high (no, I haven't done the
calculations) to cause damage to a disk, although, since we are talking about
probabalities, there is always that finite, albeit small chance; but then,
there is a infinitesimally small chance of damge from natural background
radiation. And maybe I'll win the lottery :-) Twice!
Michael Connor/Castigat ridendo mores!
Henry Spencer
>After all, EPROMs are erased by UV, do they resist the airport X-ray
>machine? I'd guess that the X-rays are heavily attenuated by the case
>of the EPROM (the top of which is transparent to UV light but not to
>X-rays), but is there real danger to EPROMs ?
People who have *tried* to erase OTP EPROMs (EPROMs in non-windowed
packages) with X-ray machines say that it seems to be effectively
impossible, even with hours-long exposures. Certainly you're not going
to do it with a device that won't fog most types of film.
--
There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim| he...@zoo.toronto.edu utzoo!henry
Pete Holsberg
=Someone who travels often should do us all a favor and experiment. Pack
=360K, 1.2M and 1.4M disks with data (one big ZIP file, perhaps) and put
=them in the luggage that will be X-rayed. Trying to unZIP the file will
=reveal if any of the data has been corrupted. If several people do this
=in several airports (a variety of X-Ray equipment) and post the results,
=we'll all know for sure.
I, for one, can report that a 1.44MB 3.5-inch MS-DOS diskette made it
unscathed through two X-ray machines -- Philadelphia and Birmingham, AL.
The diskette was in a pocket of my Lands End attache case that rode down
the belt.
Pete
Pete Holsberg
examined? -- XRay, metal detector, ???" I put a DAT tape in my checked
luggage but haven't tried to read it yet.
Joseph Jesson
I am not sure. Once, I had CMOS memory totally erased after going
through airport X-ray. This was on an HP Portable Plus laptop where
CMOS memory is used for the "C" drive. Maybe my battery was low since
I have not been able to duplicate this. Also, BESIDES CMOS, what
about FLASH memory on the new laptops...
--joe
Michael Nolan
On the other hand, I had a 720K 3.5" diskette that I forgot to take out
of my computer's carrying case before it went through the X-ray scan and
it now gives me read errors, although so far at least a couple of retries
has always done the trick. (And I've compared the results with an earlier
install and the files are identical.) Given my choice, I'd pull the
diskettes from the case.
---
Michael Nolan, no...@tssi.com "Freedom of the press is still alive in
Tailored Software Services, Inc. America, at the U. S. Mint" (Gallagher)
Lincoln, Nebraska (402) 423-1490
Laurence Chiu
I can't speak for all airlines but United x-ray checked baggage when you
check in, at the checkin area (at least in SF and LAX). And this is for
international flights. I had a couple of boxes of disks in my baggage and
they came through unscathed so it certainly wasn't magnetic. I also had
a couple of videotapes in the baggage - haven't played them yet but
they should also be unaffected.
Laurence Chiu
Carl Robinson
Magnetic scanners will like those hand-held scanners airport security
personnel use when you set off the alarm. The thingy you walk through
is also magnetic and will hose disks. X-rays will wipe out unexposed
and unprocessed film.
--
Carl Robinson ca...@netcom.com
Voice: (510) 685-4983 Fax: (510) 825-5290
Mike Shirley
Xray'ed if it's done at all.
--
Mike, WB6WUI // INET: mi...@slic.cts.com // GEnie: SLIC
Nathaniel Polish
a magnetic medium. Certainly large fields will degauss a floppy but this
is unlikely except as noted from the motors. The real problem with x-rays
is that they are high-energy radiation. They can cause small ionizations
on the surface of the disk. If the ionizations are small relative to the
size of the magnetic domains, then there is no visable problem. As the
media get denser, the domains get smaller and the problems appear. However,
modern airport x-ray equipment is very sensative and they use very weak
sources -- mostly to protect the workers.
David Lesher
# X-rays will wipe out unexposed and unprocessed film.
I'm sort of wondering about this.....
You see, I, on occasion, need to xray things mechanical. While
I've had a good safety program, and I understand the physics, I don't
know a lot about the film characterics. I just use it, you see.
Anyhow, I was using a Golden Inspector, a nice cold-cathode box. It
pulses. You typically clamp the 8x10" Poloroid X-ray film into a holder
that has a piece of phosphorescent material. It glows when struck,
exposing the film. Then you process the film and look at the results.
Anyhow, I was in a situation where I could not fit the plate holder
where needed. So, like a chump, I just used the film, and ran the
exposure up from 30 pulses to 100.
Nothing.
500 pulses
Nothing.
999
Nothing.
999, 3 times (the maximum for the Inspector until a 15 min cooldown)
Not..a...thing....
So how sensitive IS film to X-rays, anyhow?
--
A host is a host from coast to coast..wb8foz@skybridge.scl.cwru.edu
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
amco...@ulkyvx.louisville.edu
>
film designed for x-ray exposure, such as that used in medical diagnostic
radiology, has an x-ray sensitivity of less than 1%. For this reason, x rays
are converted to visible (or near visible) light energy by the use of
intensifying screens (similar to the principle you were using). Direct film
exposure is used in certain situations where high resolution is needed, but at
the cost of increased patient exposure.
Michael Connor/Castigat ridendo mores!
Josh Diamond
In article <BrwMM...@news.cso.uiuc.edu> dvsg...@uxa.cso.uiuc.edu (David Salamon) writes:
>The X-rays themselves won't do any damage, unless you're carrying something
>like 1000ASA photographic film, but they use pretty hefty electromagnets
>to focus the beam, so I never trust floppies or tapes in them, just in case.
If there are magnets in those X-ray machines, they are most likely in the
motors running the conveyer belt.
Don't forget the large transformers, and the large current needs of
X-ray machines. These generate some pretty strong magnetic fields!!
Josh Diamond
AKA Spidey!!!
--
/\ \ / /\ Josh Diamond j...@bear.com
//\\ .. //\\ AKA Spidey!!! ...!ctr.columbia.edu!ursa!jmd
//\(( ))/\\
/ < `' > \ Beauty is the purgation of superfluities. -- Michelangelo
Mike Shirley
> X-rays shouldn't bother magnetic devices (hard disks,diskettes, etc.).
> Magnetic scanners will like those hand-held scanners airport security
> personnel use when you set off the alarm. The thingy you walk through
> is also magnetic and will hose disks. X-rays will wipe out unexposed
> and unprocessed film.
I'll make up a test disk today and try it out on a couple of
magnetometers and hand-held scanners. Repeatitive passes, close
proximity to the coils. In other words, worst case senerio.
Danny Halamish
|>
|> And while we are asking for facts (which are a rare find on this
|> newsgroup): How about EPROMs and similar stored-charge memory devices?
|> After all, EPROMs are erased by UV, do they resist the airport X-ray
|> machine? I'd guess that the X-rays are heavily attenuated by the case
|> of the EPROM (the top of which is transparent to UV light but not to
|> X-rays), but is there real danger to EPROMs ?
|>
all. Both have survived the X - rays.
I have had audio tapes X-rayed in airports several times and did not notice
any differnce.
--
-Danny
Jeff Gruszynski
You'd probably need mega or giga Rad X-ray levels before you'd affect the
magnetic media. In a previous life I worked with radiation testing hardened
memories including both semiconductor and magnetic types. In the latter
the magnetic memory cells were never the issue, but rather getting the
semiconductor support circuitry to keep up with what the magnetics could
take. The cell sizes of these magnetic memories (bubble and
magnetoresistive) were smaller than the domain size of most floppies.
Probably a bigger threat to floppies, tapes, etc. would be the HV
supplies and fields generated by the E-beam in the X-Ray tube, **if even
this**.
Jeff
Chris Best
I have sent a running camcorder through an airport x-ray machine,
and watched the tape later. The tape was fine, with no apparent
effects.
David Salamon
>X-rays will not harm magnetic tapes at all. However, the enormous magnets
>that X-ray tubes use to focus their electron beam might very well damage
>tapes.
I seriously doubt that there is any focussing of the eletrons at all. I think
there is simply a high voltage between a small hot cathode and a larger
target. If the target is flat (for example) and much larger than the cathode,
then the electrons will follow the field lines and all impact roughly
perpendicular to the surface. No focussing necessary. After all, we don't
care WHERE the electrons hit the target, just that they hit with the correct
momentum.
As others have mentioned, however, the high voltage is produced by a
transformer, which will create a magnetic field. Metal shielding of course
will not stop this field, so it could affect magnetic media. It all
depends on where the transformer is placed with respect to the conveyer belt.
amco...@ulkyvx.louisville.edu
> I seriously doubt that there is any focussing of the eletrons at all. I think
> there is simply a high voltage between a small hot cathode and a larger
> target. If the target is flat (for example) and much larger than the cathode,
> then the electrons will follow the field lines and all impact roughly
> perpendicular to the surface. No focussing necessary. After all, we don't
> care WHERE the electrons hit the target, just that they hit with the correct
> momentum.
>
electrons are normally focused by electrostatic means. We do care where the
electrons hit the target because this will affect the resolution of the image
produced by the x-ray beam and the heat build-up in the anode. It is true that
x rays will be produced isotropically in the target by bremsstrahlung (and to a
lesser extent by electron transitions <characteristic radiation>) but if the
target is angled self-absorption in the anode will produce a useful beam in the
desired direction.
Michael Connor/Castigat rideno mores!
Mike Shirley
> On the other hand, I had a 720K 3.5" diskette that I forgot to take out
> of my computer's carrying case before it went through the X-ray scan and
> it now gives me read errors, although so far at least a couple of retries
> has always done the trick. (And I've compared the results with an earlier
> install and the files are identical.) Given my choice, I'd pull the
> diskettes from the case.
That certainly is the safest way to play. But for what it's
worth, I've done the following...
I formated 2 3.5 HD floppies and wrote a 503K ZIP file to each.
I ran disk A through the X-Ray machine 1 time, then walked
through the metal detector (magnetometer) twice, and lastly ran the
hand scanner over/around the floppy twice. This was to simulate
a normal pass through airport security, more or less.
I then took disk B and ran it through the X-Ray machine 10 times,
then placed the floppy inside the walk-thru metal detector and
ran it around the 3 walls of the machine, placing the floppy as
close as possible to the mag coils. I then ran the floppy
through 10 times as if I were carrying it through normally. Next
20 or so passes with the hand-held metal detector.
I then ran "CHKDSK" and "PKUNZIP -t" to test the ZIP file.
Both floppies passed fine and had identical values before and
after the "scanning". Our machines are 14 months old and were then
the "latest in technology" at the time of purchase.
Bottom line, it appears that late model hardware will not cause data
loss on floppy discs. But, as they say...your mileage may vary...
Matthew Kleinmann
--
Alchemy International, Ithaca NY
mat...@alchemy.tn.cornell.edu
mat...@alchemy.ithaca.ny.us
Public Access Unix
Simon Rockliff
|> smck...@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:
|>
|> >The X-rays themselves won't do any damage, unless you're carrying something
|> >like 1000ASA photographic film, but they use pretty hefty electromagnets
|> >to focus the beam, so I never trust floppies or tapes in them, just in case.
|>
|> electromagnetic wave, including X-rays. Remember superposition of fields?
|> People have been trying to focus X-rays for many years without much success.
|> Virtually all X-ray machines just use incoherent, unfocussed X-rays.
|>
|>
|> David
|>
|> --------------------------------------------------------------
|> David Salamon Physics Graduate Student (Slave
Perhaps what Steve McKinty meant by beam was a high energy electron beam which is
used to bombard a target to produce the X-rays. Searching in the depths of my
memory I recall that my 1978 vintage Physics textbook had a picture of an
electron beam, accelerated by a high electric potential, and focussed by an array
of electromagnets onto a tungsten target, producing X-rays. However, I have no
idea if the modern X-ray machines use different methods to produce the X-rays.
Simon Rockliff
Michael Judson
computers. I can see the implications of an X-ray affecing electromagnetic
material on the disk, but does anyone know the technical aspects?
Iskandar Taib
>Not quite. Photographic film has resiprosity (sp). For very low
>exposure levels, it takes much more time. You are working very low
>on the knee of the gamma curve.
You mean "reciprocity failure". Reciprocity means behaving like it
ought to, i.e. an exposure like f16 @ 1/8 sec = f8 @ 1/16 sec.
Multiple exposures to X-rays will eventually effect the film. If the
film has been exposed you will actually start to see the effects in
the highly exposed areas of the images.
--
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Iskandar Taib | The only thing worse than Peach ala
Internet: NT...@SILVER.UCS.INDIANA.EDU | Frog is Frog ala Peach
Bitnet: NTAIB@IUBACS !
David Lee
>In article <1992Jul30....@tc.cornell.edu> mat...@alchemy.tn.cornell.ed
>u (Matthew Kleinmann) writes:
.>Not quite. Photographic film has resiprosity (sp). For very low
.>exposure levels, it takes much more time. You are working very low
.>on the knee of the gamma curve.
>You mean "reciprocity failure". Reciprocity means behaving like it
>ought to, i.e. an exposure like f16 @ 1/8 sec = f8 @ 1/16 sec.
>Multiple exposures to X-rays will eventually effect the film. If the
>film has been exposed you will actually start to see the effects in
>the highly exposed areas of the images.
This was the way the old dosimeter for radiation works.. Right?? You
wear a "badge" with a strip of film and the cummulative effects of
the radiation was "measured" by the film's sensitivity to exposure of
the radiation.
.
.
...
Mustafa Soysal
I heard that there are two kind of x-ray inspection machines, the ones at
the gate are probably the soft kind. I would assume that the checking of
luggage transferred from connections are done with hard x-rays.
Shipments of tape drives and hard disks I get have large banners imprinted
saying "magnetic media enclosed, do not x-ray".
One important detail with physics is, that certain levels of energy applied
to the material will change its magnetic characteristics. Temperature is
one factor that can change the magnetic properties of the material, there is
an effect known as the Curie Temperature, at which iron looses its magnetic
properties and changes crystall structure probably permanently. Many of the
dense data recording methods rely on a certain working point at the materials
magnetic properties, if the material changes as a result of high energy
exposure, the recording/retrieving method may not work some or at all. (I
could also imagine that being able to read it after exposure may not mean
that you can read it after trying to write on it.)
The results would not only depend on the media type, but also what kind of
radiation they were exposed to, and for how long. I don't think you can
experiment reliably by just taking it with you on the trip. Imagine the
case where they pass it thru nonstop while you test, and everything seems
fine. But then next time, they may stop the conveyor to take a good look at
it, or it may get stuck in the machine for longer than usual...
Mustafa Soysal
Iskandar Taib
>This was the way the old dosimeter for radiation works.. Right?? You
>wear a "badge" with a strip of film and the cummulative effects of
>the radiation was "measured" by the film's sensitivity to exposure of
>the radiation.
Yup.
We still wear them, too.
A photography magazine once published some affected images. You
could see "ghosts" in the very light areas of the image, but not
in the dark.