Closing in on the border between primordial plasma and ordinary matter
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 Energys 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 datapresented at the Quark Matter 2012 international conferencecome 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.