10 November 2005

Tracking ‘messengers from the extreme universe’
University of Leeds scientists will join celebrations in Argentina this week to mark the progress of the Pierre Auger Observatory, a project to study the highest-energy cosmic rays. Around 120 guests from the science world will join project members from 16 countries at the 3-day programme including presentations, a science fair for local schoolchildren and the report of the first physics results from the observatory.

The $50m Pierre Auger Observatory is exploring the mystery of high-energy cosmic rays of unknown origin – charged particles showering the earth at energies above 1019 electron volts, about 10 million times higher than the world's highest-energy particle accelerator. To witness these extremely rare events, the observatory is constructing an array of 1600 detectors spread over 3000 square kilometres – roughly the size of the area inside the M25 - in Argentina's Mendoza Province. Each detector contains 3000 gallons of water. Surrounding the array is a set of 24 telescopes which, on clear moonless nights, observe the ultraviolet fluorescence light produced as cosmic ray shower particles travel through the atmosphere.

Leeds experts – including Dr Paul Clark from the school of electronic and electrical engineering – designed and delivered the communications network which links the detectors to the central data collection system. Intellectual capital was also brought from the Haverah Park project, a research site operated by the University of Leeds physics department until 1987.

Professor Alan Watson of the University of Leeds conceived the Auger experiment together with Nobel Prize winner Jim Cronin of the University of Chicago, who said: "These highest-energy cosmic rays are messengers from the extreme universe.” Professor Watson added: “They represent a great opportunity for discoveries: how does nature create the conditions to accelerate a tiny particle to such an energy? Tracking these ultrahigh-energy particles back to their sources will answer that question."

While a northern hemisphere site has not yet been funded, the collaboration is working to establish a northern hemisphere partner of the southern observatory, likely to be based in southeastern Colorado in the US. With observatories in both hemispheres, the Auger collaboration will have the opportunity to view the entire universe from every direction.

Commenting on the observatory’s progress, the chief executive of the UK's Particle Physics and Astronomy Research Council [PPARC], Professor Keith Mason, said: "The Pierre Auger Observatory is a remarkable example of international collaboration and I am particularly proud that the UK was involved at its inception and that our scientists continue to play a key role in this project."

"Once more science stands at the threshold of resolving a fundamental question that has so far eluded mankind – the source of high energy cosmic rays,” said Professor Mason. “And I look forward with great interest to Auger's quest to unravel one of Nature's most intriguing mysteries."

Notes for editors
1. For more information on the Pierre Auger Cosmic Ray Observatory see www.auger.org/ or see also the Particle Physics and Astronomy Research Council's press release at www.pparc.ac.uk/Nw/auger_celebration.asp
2. For Pierre Auger Observatory images see www.auger.org/observatory/2004.html