Using high-speed collisions between gold atoms, scientists thinkthey have re-created one of the most mysterious forms of matter in theuniverse -- quark-gluon plasma. This form of matter was present duringthe first microsecond of the Big Bang and may still exist at the coresof dense, distant stars.
UC Davis physics professor Daniel Cebra is one of 543 collaboratorson the research. His main role was building the electronic listeningdevices that collect information about the collisions, a job hecompared to "troubleshooting 120,000 stereo systems."
Now, using those detectors, "we look for trends in what happenedduring the collision to learn what the quark-gluon plasma is like," hesaid.
"We have been trying to melt neutrons and protons, the buildingblocks of atomic nuclei, into their constituent quarks and gluons,"Cebra said. "We needed a lot of heat, pressure and energy, alllocalized in a small space."
The scientists produced the right conditions with head-on collisionsbetween the nuclei of gold atoms. The resulting quark-gluon plasmalasted an extremely short time -- less than 10-20 seconds, Cebra said.But the collision left tracings that the scientists could measure.
"Our work is like accident reconstruction," Cebra said. "We seefragments coming out of a collision, and we construct that informationback to very small points."
Quark-gluon plasma was expected to behave like a gas, but the datashows a more liquid-like substance. The plasma is less compressiblethan expected, which means that it may be able to support the cores ofvery dense stars.
"If a neutron star gets large and dense enough, it may go through aquark phase, or it may just collapse into a black hole," Cebra said."To support a quark star, the quark-gluon plasma would need rigidity.We now expect there to be quark stars, but they will be hard to study.If they exist, they're semi-infinitely far away."
The project is led by Brookhaven National Laboratory and LawrenceBerkeley National Laboratory, with collaborators at 52 institutionsworldwide. The work was done in Brookhaven's Relativistic Heavy IonCollider (RHIC).
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