The ATLAS Experiment, in which the Brandeis High Energy Physics Group participates, has announced evidence for a quark-gluon plasma. This is a state of matter that existed for the first few microseconds after the birth of the Universe when quarks and gluons roamed freely before the Universe cooled enough for them to combine into the protons and neutrons that make up the matter we know today. A phenomenon known as jet quenching, which is considered evidence for the production of a quark-gluon plasma, has been observed and accepted for publication in Physical Review Letters.

ATLAS is one of the experiments at the Large Hadron Collider (LHC). We have just completed a successful first year of running. At the end of the run we studied Heavy Ion collisions (lead on lead). Head-on collisions by two lead nuclei are expected to produce a quark-gluon plasma. In this process, the products of hard collision (jets) are reabsorbed by the plasma. Observation of this process by ATLAS is considered evidence for the production of a quark-gluon plasma. Being able to produce and study this phenomenon will help us understand behavior of matter at the very beginning of the Universe.

More information about this phenomenon and details about the ATLAS experiment can be found at the http://atlas.ch/ web site. The Brandeis High Energy Physics Group includes professors Jim Bensinger, Craig Blocker, Larry Kirsch, Gabriella Sciolla, Hermann Wellenstein and research scientist Christoph Amelung.