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NMSU researchers helping to re-create Big Bang conditions

Scientists who smash atoms at the Department of Energy's Brookhaven National Laboratory, including a team of physicists from New Mexico State University, are more confident than ever that they have produced a state of matter that existed just microseconds after the Big Bang.

Some of the PHENIX project's muon detector group are shown posed in front of the detector's south muon arm in this April 2002 photo. Stephen Pate of NMSU's physics faculty is seated at far left, front row.

researchers so far have stopped short of saying for certain they have created the super-heated subatomic soup known as quark-gluon matter.

"What we are saying is that the evidence is very strong," said physicist Stephen Pate, a member of the NMSU team that has been participating in experiments at Brookhaven's Relativistic Heavy Ion Collider (RHIC) over the past five years. "There is a lot of additional data to be analyzed."

An important part of the data that could confirm the findings was collected by a research group with a strong New Mexico contingent. Scientists from NMSU, the University of New Mexico and Los Alamos National Laboratory are working on the PHENIX Experiment, one of four international collaborations collecting data from the high-energy particle collisions that occur at RHIC.

Scientists at the huge RHIC facility accelerate subatomic particles such as gold ions - the nuclei of gold atoms stripped of the electrons that normally encircle them - to near the speed of light around two 2.4-mile rings, creating head-on collisions that generate high energy densities and temperatures of about a trillion degrees.

The force and heat are so great that particles known as quarks and gluons, which normally are inseparably bound within an atom's protons and neutrons, fly free for an instant, mimicking a state that existed briefly when the universe was only a fraction of a second old.

Brookhaven officials announced April 18 that experiments at RHIC had produced a state of quark-gluon matter that behaves surprisingly like a liquid. At such high temperatures, they had expected a plasma or gas of free quarks and gluons instead of a fluid.

"It's like steam versus water," said Gary Kyle, head of the NMSU physics department and another member of the PHENIX team. "We thought we were making quark steam but it turned out to be a quark liquid."

Like water poured from a pitcher, the quark-gluon matter created by the experiments holds together as a fluid instead of scattering as a gas, Pate said. In the April 18 announcement, the substance was described as a nearly "perfect" liquid, with particles flowing together in a highly coordinated way.

The discovery gives scientists new insight into the earliest moments of the universe, Pate said. "This helps us learn about a stage the universe went through in the first microseconds after the Big Bang," he said. "It pushes the clock back another fraction of a microsecond closer to the beginning of the universe."

Working with Kyle and Pate on the PHENIX project are Vassili Papavassiliou, another NMSU physics faculty member, and Xiaorong Wang, a postdoctoral researcher who spends most of her time at the Brookhaven laboratory on Long Island. Graduate students also participate in the project.

The NMSU scientists and their colleagues from UNM and LANL are collecting and analyzing data from the PHENIX project's muon detectors, which record the behavior and characteristics of subatomic particles known as muons that are among the byproducts of the gold ion collisions.

By analyzing the energy and momentum of these muons, the scientists can determine how many particles known as J/psi particles were created in a collision. Pinning down that information will be an important confirmation that the experiments have indeed produced a guark-gluon matter, Pate said.

He said the muon detector group hopes to complete its data analysis in time to present at a large international science conference, Quark Matter 2005, in Budapest, Hungary, in August.

Some components of the PHENIX muon detectors were built by NMSU students in 2000, under the guidance of Greg Moran of NMSU's Physical Science Laboratory. Other parts were built at Los Alamos and UNM, and at various other locations throughout the world, before the huge instruments were assembled at the Brookhaven lab.

Powerful particle accelerators like the one at Brookhaven are one way of learning about the conditions that existed in the early universe, Kyle said. Another way is to study very distant astronomical objects, "because that is the light from the early universe," he said.

New Mexico State University, through its physics and astronomy departments, is involved in both kinds of research, he noted.