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New
Release -- Superconductor Week does not edit or endorse the following
news release:
New technique for easily identifying explosives in
luggage
Osaka, Japan, 22 January 2007: Scientists in
Japan have developed a new technique for sensing explosives in luggage and
landmines. The paper, published today in the
Institute of Physics journal Superconductor Science and Technology
describes how radio waves can be used to identify specific explosives, such as
TNT. The new method could be used in future to screen baggage at airports.
The new technique has advantages over traditional
methods of detection: unlike x-rays that are currently used in airport security,
it can distinguish between different types of white powder from flour and salt
to drugs and explosives. It can also be used to detect landmines, an advance on
the traditional method of using a metal detector which cannot distinguish
between bits of metal in the ground and an actual mine.
Professor Hideo Itozaki, one of the authors of the
paper at
Osaka University said: “Until now it has been very difficult to detect
specific explosives such as TNT because they contain atoms of nitrogen that
vibrate at very low frequencies. The natural frequency at which the nucleus of
an atom vibrates at is called its resonant frequency and the lower this is, the
harder it is to detect what atoms are present in a molecule which in turn makes
it harder to define what the molecule or substance is.”
The technique relies on nitrogen nuclear quadrupole
resonance (NQR) which detects atoms of nitrogen (an element found in many
explosives, including TNT) in different positions in a molecule. For example an
atom of nitrogen attached to a carbon atom will have a different resonance to
one attached to an oxygen atom. Because the molecular structure of each
explosive is different, the resonant frequency will be different.
Professor Itozaki continued: “We have successfully
developed a machine that can pick up very low resonant frequencies by using a
SQUID (superconducting quantum interference device). The SQUID operates at a
temperature of 77 Kelvin (minus 196 degrees centigrade) which we achieve by
using liquid nitrogen. This will not hinder the equipment from being used in
places such as airports as liquid nitrogen is becoming much easier to deal with
and is already routinely used in hospitals and laboratories.”
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