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- Path: sparky!uunet!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!unixhub!falcon.SLAC.Stanford.EDU!ralph
- From: ralph@falcon.SLAC.Stanford.EDU (Ralph Becker-Szendy)
- Newsgroups: sci.electronics
- Subject: Re: Airport X-Rays
- Message-ID: <4836@unixhub.SLAC.Stanford.EDU>
- Date: 24 Jul 92 22:55:44 GMT
- References: <1992Jul13.020123.3132@mccc.edu> <BrwMMA.6rG@news.cso.uiuc.edu> <22754@oasys.dt.navy.mil>
- Sender: news@unixhub.SLAC.Stanford.EDU
- Organization: Stanford Linear Accelerator Center
- Lines: 39
- Nntp-Posting-Host: falcon.slac.stanford.edu
-
- In article <22754@oasys.dt.navy.mil> dlee@oasys.dt.navy.mil (David Lee) writes:
- >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 RALPH@SLACVM.SLAC.STANFORD.EDU
- Stanford Linear Accelerator Center RALPH@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.
-