CERN-EX-1011252 tirage 04 . Events recorded by the ALICE experiment from the first lead ion collisions, at a centre-of-mass energy of 2.76 TeV per nucleon pair. (Credit: © CERN)
After less than three weeks of heavy-ion running, the three experiments studying lead ion collisions at the Large Hadron Collider have already brought new insight into matter as it would have existed in the very first instants of the Universe's life. The ALICE experiment, which is optimised for the study of heavy ions, published two papers just a few days after the start of lead-ion running.
Now, the first direct observation of a phenomenon known as jet quenching has been made by both the ATLAS and CMS collaborations. This result is reported in a paper from the ATLAS collaboration accepted for publication in the journal Physical Review Letters. A CMS paper will follow shortly, and results from all of the experiments will be presented at a seminar on Dec. 2 at CERN (the European Organization for Nuclear Research). Data taking with ions continues to Dec. 6.
"It is impressive how fast the experiments have arrived at these results, which deal with very complex physics," said CERN's Research Director Sergio Bertolucci. "The experiments are competing with each other to publish first, but then working together to assemble the full picture and cross check their results. It's a beautiful example of how competition and collaboration is a key feature of this field of research."