Image of the particle tracks left from an exploding nuclear fireball in the ALICE detector. Image credited to ALICE/CERN.
Professors Steffen Bass and Berndt Mueller rejoiced this month at the news that the Large Hadron Collider started its program of collisions of lead nuclei at unprecedented energies, almost 15 times higher than those previously explored at Brookhaven National Lab's Relativistic Heavy Ion Collider (RHIC). The Large Hadron Collider (LHC) is at the European Organization for Nuclear Research (CERN) near Geneva, Switzerland.
The lead nuclei are being collided as part of three large international experiments at the LHC called ALICE, ATLAS and CMS which seek to create a quark-gluon plasma, a state of matter that is believed to have existed microseconds after the birth of our universe. Bass and Mueller did not have to wait long to see the first results: The ALICE Collaboration published its first two data analyses just 10 days after seeing the first collisions. In view of the complexity of the detector and the need to analyze thousands of particle tracks left from the exploding nuclear fireballs (see picture), this shows how quickly science can move once everything is in place. Of course, the feat was preceded by more than 10 years of planning, construction, and preparation. Mueller and Bass are working with their postdocs Hannah Petersen and Guangyou Qin and their students to make sense of the results from ALICE. They posted a first assessment of the implications of the LHC data for our knowledge of the properties of hot quark-gluon matter on the Virtual Journal on QCD Matter, a site hosted by Duke members. For starters, the quark-gluon plasma produced at the LHC is at least 30 percent hotter than that created at RHIC, and it still looks like a nearly "perfect fluid" under the even more extreme conditions. This came as a surprise to many theorists (but not the Duke group!) who speculated that the quark-gluon liquid would turn into a gaseous plasma at the higher temperatures reached at the LHC. A lot more data are certain to emerge soon, so watch out for more news!