A NEW career as oil prospectors beckons for atomic physicists. The tiny
particles called solar neutrinos that stream out from the Sun鈥檚 core might be
used to prospect for oil in the Earth鈥檚 crust鈥攖hough putting the idea into
practice is still a problem.
Neutrinos are extremely light particles produced by nuclear reactions in
stars. The three types鈥攅lectron, muon and tau neutrinos鈥攆lip from
one type to another as they flood out from stars at close to the speed of light
(快猫短视频, 5 August 2000, p 4).
Neutrinos from the Sun are
constantly whizzing right through the Earth, and detectors can pick up the tiny
number that interact with atoms within the Earth.
Now Ara Ioannisian and Alexei Smirnov of the International Centre for
Theoretical Physics in Trieste, Italy, say that these neutrinos could reveal the
location of oil reserves. The rate at which the particles flip from one type to
another as they pass through the Earth depends on the density of the material
they鈥檙e travelling through. So the numbers of electron neutrinos emerging on the
night-side of the Earth in any given spot will depend on the type of
structures鈥攆or example, rock layers or oil-filled cavities鈥攖hey have
traversed.
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Ioannisian and Smirnov calculate that an oil pocket located up to a few tens
of kilometres or less under the Earth鈥檚 surface could alter the number of
electron neutrinos detected by up to 0.3 per cent. A detector could measure this
signal from two angles as the Earth rotates and locate the oil by
triangulation.
But you won鈥檛 be seeing this technique in use any time soon. Ioannisian says
that with current technology, neutrino detectors sensitive enough to do the job
would have to be huge鈥攁bout four times the size of a soccer stadium, and
weighing about 10 million tonnes. They would also have to be able to rove
around, probably on deep-sea submarines.