Reporter 434, 29 March 1999

Physics leads new search for rays from space

Cosmic rays so rare - one strikes the University campus every 150 years - are being hunted by University researchers using 1,600 tanks of Argentinian water.

The source of these high-energy particles, it is believed, could reveal the origins and evolution of the Universe. Millions of low-energy particles from local galaxies arrive on earth every day, but physicists have not yet been able to find the source for their highest-energy equivalents.

The rays themselves cannot be seen, but their speed and direction can be determined by detecting secondary cascades of particles they create and send towards the earth.

University professor Alan Watson and Nobel Prize winner James Cronin at Chicago University (an honorary Leeds graduate) are jointly leading a $50m international project to construct a cosmic ray observatory in Argentina - the largest astronomical collaboration in the world.

The Pierre Auger project - named after the physicist who discovered the shower effect - will place water tank-based detectors over an area the size of Lancashire to monitor the ongoing bombardment. There is also an optical detector to pick up signals at night.

The array of detectors will be placed over a mile apart from each other - making it impractical to join them with wires or cables. A joint project between Physics and Astronomy and Electrical and Electronic Engineering will develop communications allowing the 1,600 detectors to talk to each other. "The electric engineers are vital to the project because they have invented an original method of data transmission," said Professor Watson.

"Only a dozen or so of these really high energy particles have ever been recorded," he said. "With the new observatory we should be able to observe one every few days. It's very exciting - we will be able to do in two weeks work that took twenty years at our own observatory at Haverah Park."

The University project will be supported by a £1.75m grant from the particle physics and astronomy research council.

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