News: Auger Press Release

Friday, June 8, 2001
Media contact: Judy Jackson
Fermilab Office of Public Affairs
630-840-3351

First Cosmic Ray Events Detected by the Pierre Auger Observatory

Scientists of the Pierre Auger Cosmic Ray Observatory announced this week the detection of high energy particles from space. The new device that recorded the particles is the first of 30 "atmospheric fluorescence telescopes" that will be part of the Auger Observatory.

An energetic cosmic ray initiates a cascade of particles which grows to more than a billion charged particles moving together at the speed of light through the atmosphere. Like charged particles in a fluorescent light bulb, they cause the air to emit light which can be observed from a distance. Large collecting mirrors and fast photodetectors enable scientists to measure from a distance of 20 kilometers this luminosity, which is equivalent to a flashlight bulb moving at the speed of light. A particle cascade lasts only about 10 millionths of a second.

The air fluorescence telescopes are part of the giant Auger Observatory that is being built near Malargüe in Argentina's Mendoza Province by physicists from 19 contributing countries. The observatory will also have 1,600 particle detectors distributed over an area of 3,000 square kilometers to detect samples of the cascade particles directly. Cosmic rays recorded simultaneously by both types of detectors will be of special value to scientists studying the universe's highest energy particles.

There is no satisfactory explanation for what produces high energy cosmic rays. Scientists are convinced that the Auger Observatory will discover new fundamental physics or some surprising astrophysics by resolving this cosmic ray mystery.

Construction of the full Auger Observatory is scheduled for 2002-2004, after all aspects of the design have been tested this year. The cost of the observatory in Mendoza is $50 million. A matching observatory is planned for the northern hemisphere as well. The project spokesperson is Nobel laureate James W. Cronin, and Alberto Etchegoyen is the spokesperson for the southern hemisphere.

The Province of Mendoza, Argentina, provided the special building at Los Leones that will house the first six air fluorescence telescopes.