Mike,
I work in this industry (concealed weapons detection) and can give you an
answer.
1. Nomenclature: While often referred to as magnetometers, its really an
"electromangetometer" if you will. Conventional walk-thru portals use an
active AC (as in not DC) magnetic field generated by coils of copper wire on
each side. A metal object in the field will generate "eddy currents" which
cause measureable voltage fluctuations in the copper wire coils. This
process is different from a DC magnetic field which is the "traditional"
field people think of when they think "magnet" and uses a permanent physical
magnet.
2. The physical size, orientation, and composition of the object all
contribute to its detectability in this process. Obviously, theses
detectors are optimized to detect guns first, then knives. Actually, they
must only actually detect 3 specific models of guns and (currently) no
knives. (thank the FAA).
The biggest problem with current metal detectors is that in order to detect
the smallest required gun on the FAA 3-gun test (a tiny .22LR revolver) its
so sensitive that it detects alot of other things, too.
Its also possible to shield small objects so that their signal is below the
alarm threshold (like maybe a bone plate and some screws??)
I do agree completely, though, that US airport security blows.
-----Original Message-----
From: Mike Lorrey [mailto:mlorrey@datamann.com]
Sent: Wednesday, September 19, 2001 9:49 AM
To: extropians@extropy.com; exi-freedom@yahoogroups.com
Subject: New Airport Security still SUCKS
Mom went through a magnetometer the other day at the airport. She
happens to have a big titanium plate and screws in her arm. Did the
buzzer go off? Nope. Puzzled, she told the security person about the
plate and asked why the detector didn't detect this large metal object
in her body. The security person said "Just move along."
Its rather obvious that titanium is not a magnetic metal, so it is
undetectable by a magnetometer. It's also obvious that it is a rather
useful material to use in the manufacture of weapons: knives, clubs,
even firearms.... and airport magnetometers cannot detect them.
Think about this for a minute. This means that the only real means of
ensuring that passengers are not armed is to strip and cavity search
every airline passenger.
Think about the implications: since it is therefore impossible to
prevent all passengers from being armed unless we choose to live in a
big brother police state, we MUST have armed people on every flight.
This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:40:52 MDT