Summary -
(Aug 1, 2005)
Physicists have used the Brookhaven
National Laboratory's Relativistic Heavy
Ion Collider to create quark-gluon
plasma; a mysterious form of matter that
was probably present in the first
moments after the Big Bang. The team
created it by smashing the nuclei of
gold atoms together at relativistic
speeds. The resulting explosion of
particles lasted just 10-20 seconds.
Astronomers think that large neutron
stars might go into a quark-gluon phase
before they collapse into black holes.
Full Story -
|
 |
|
Degree of
interaction among quarks in
liquid gold-gold collisions.
Image credit: RHIC Click
to enlarge |
Using high-speed
collisions between gold atoms,
scientists think they have re-created
one of the most mysterious forms of
matter in the universe -- quark-gluon
plasma. This form of matter was present
during the first microsecond of the Big
Bang and may still exist at the cores of
dense, distant stars.
UC Davis physics professor Daniel Cebra
is one of 543 collaborators on the
research. His main role was building the
electronic listening devices that
collect information about the
collisions, a job he compared to
"troubleshooting 120,000 stereo
systems."
Now, using those detectors, "we look for
trends in what happened during the
collision to learn what the quark-gluon
plasma is like," he said.
"We have been trying to melt neutrons
and protons, the building blocks of
atomic nuclei, into their constituent
quarks and gluons," Cebra said. "We
needed a lot of heat, pressure and
energy, all localized in a small space."
The scientists produced the right
conditions with head-on collisions
between the nuclei of gold atoms. The
resulting quark-gluon plasma lasted 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 see
fragments coming out of a collision, and
we construct that information back to
very small points."
Quark-gluon plasma was expected to
behave like a gas, but the data shows a
more liquid-like substance. The plasma
is less compressible than expected,
which means that it may be able to
support the cores of very dense stars.
"If a neutron star gets large and dense
enough, it may go through a quark 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 Lawrence
Berkeley National Laboratory, with
collaborators at 52 institutions
worldwide. The work was done in
Brookhaven's Relativistic Heavy Ion
Collider (RHIC).
Original Source: UC
Davis News Release
