Department of Physics & Astronomy

Relativistic Heavy-Ion Physics

Participating Faculty

Prof. K. Barish, Prof. R. Seto

Why are the constituents of the proton confined? Where does its mass come from?

These are the questions that have driven us to utilize the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory.

All of the phase transitions that we are able to observe so far on earth involve the electromagnetic interaction, for example, the melting of ice, the formation of steam, or the magnetization of metals. We are seeking to see, for the first time on earth, an entirely new form of phase transition, that involving the Strong Interaction or quantum chromodynamics (QCD) in which a gas of quarks and gluons called a “Quark-Gluon Plasma” (QGP) condenses to form protons, neutrons and other hadrons.  This is a remarkable transition because we believe that it also is the transition which gives rise to the protons and neutrons that make up most of the matter we see here on earth.  Another curious thing occurs as protons and neutrons condense out of the hot vacuum that makes up the QGP that is presumably created in the most violent collisions.

Shortly after the big bang the universe went through a period of fantastic expansion, dubbed inflation. What could cause such a cataclysmic event?  Just as the explosive power of turning water into steam powered much of the industrial revolution, it is believed that a phase transition of some sort – no one is sure what – powered inflation.

Our group is part of the PHENIX collaboration, which is one of the two major detectors at RHIC. This detector is optimized for the study of electrons, muons, and photons. It also has an extensive capability of measuring hadronic signatures of the Quark-Gluon Plasma.

RHIC can also collide polarized protons in addition to heavy-ions (see the separate UC Riverside spin physics page). The UC Riverside spin and heavy-ion physics groups work together closely.

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Maynard, Bonnie; Chair's Assistant, Academic Personnel
E-mail: bonnie.maynard@ucr.edu