Closing in on the Border Between Primordial Plasma and Ordinary Matter

UPTON, NY - Scientists taking advantage of the versatility and new
capabilities of the Relativistic Heavy Ion Collider (RHIC), an atom
smasher at the U.S. Department of Energy's Brookhaven National Laboratory,
have observed first glimpses of a possible boundary separating ordinary
nuclear matter, composed of protons and neutrons, from the seething soup
of their constituent quarks and gluons that permeated the early universe
some 14 billion years ago. Though RHIC physicists have been creating and
studying this primordial quark-gluon plasma (QGP) for some time, the
latest preliminary data-presented at the Quark Matter 2012 international
conference -come from systematic studies varying the energy and types of
colliding ions to create this new form of matter under a broad range of
initial conditions, allowing the experimenters to unravel its intriguing
properties.

"2012 hasto zero when bubbles
from all collision events are looked at together.

"Such symmetry-violating bubbles are of crucial interest in the early,
high-temperature history of the universe, where analogous bubbles are
speculated to have played a central role in producing the preponderance of
matter over antimatter in today's universe, enabling our existence,"
Vigdor said.

The disappearing hints of charge separation may be another signal that the
lower-energy RHIC collisions are no longer producing QGP. But it's also
conceivable that the hints arise instead from a "background" phenomenon
that is related to the almond-like shape of the overlap region formed when
two spherical gold ions collide in not quite head-on fashion.

Head-on collisions of football-shaped uranium ions aligned in upright
positions like footballs set for kick-off-conducted for the first time
during the 2012 RHIC run, and made possible by a new ion source