Experimental research in high energy nuclear physics

Prof. Claude Pruneu, Prof. Joern Putschke, Prof. Sergei Voloshin

Relativistic heavy ion physics involves the study of nucleus-nucleus collisions at high energies in order to understand the behavior of extended nuclear matter under extreme conditions of high density and temperature. The primary goal is to reach the phase transition from ordinary nuclear matter to a quark-gluon plasma.

This field of research offers the only means to study the fundamental theory of strong interactions in the high-density limit and to observe directly the parameters of the predicted phase transition. It may also enable us to study the physical properties of the Quantum Chromodynamics vacuum state which reflects manifestly long-range phenomena over large distance scales, not realizable in collisions of elementary particles. Relativistic collisions of heavy ions provide information on the equation of state of nuclear matter at densities relevant to the interior of neutron stars and furthers our understanding of the beginning of the universe.

The Wayne State University experimental heavy ion group is supported by the U.S. Department of Energy and consists of four faculty, four research associates and post-docs, and several graduate students. Members of the group have been active collaborators in fixed target experiments E814, E877, E864, E896, E941 at the BNL AGS, as well as experiments NA45 and NA49 at the CERN SPS. A total of 47-refereed publications were produced by the above experiments. Of these, 30 were lead by members of our group. Nine Wayne State students received a degree based on their participation to these experiments.

STAR Experiment
STAR Experiment

During the last decade, members of the group have focused their activities on the development, deployment, and operation of the STAR Experiment at the Relativistic Heavy Ion Collider, and on the analysis of the large body of data it produces. Members of the group have played critical roles in the development and deployment of the STAR experiment. This includes project management responsibility for the Silicon Vertex Tracker, SVT (Professor Bellwied), the Electromagnetic Calorimeter, EMC (Professor Cormier), the online, and the integrated tracker (ITTF) projects (Professor Pruneau). The STAR Collaboration has published over 100 refereed papers in top physics journals.

Many of these papers involved members of the Wayne State group as primary authors, thereby making the group a strong leader of RHIC physics as well as its associated technologies. The group physics interests and analysis activities cut across many areas relative to the discovery and characterization of the quark-gluon plasma (QGP). In essence, the group has contributed to virtually all aspects the RHIC heavy ion program. Specific topics include the discovery (Professor Voloshin, first STAR paper) and study of flow at RHIC; the study of event-by-event fluctuations of transverse momentum, net charge, and chemical abundances; measurements of two-particle short (HBT) and long-range correlations; measurements of strangeness production, equilibration, and flow; study of high pt particle production, and azimuthal correlations; and finally hard-probe studies with the EMC. Six Wayne State students have completed their degree based on their research with the STAR experiment.

CERN Large Hadron Collider
CERN Large Hadron Collider

Members of the group are now members of the ALICE Collaboration and are conducting a vigorous research program at the CERN Large Hadron Collider with studies on proton-proton collisions and lead on lead ultra-relativistic collisions. The group, under the leadership of Professor Thomas Cormier, has lead the construction and deployment of the ALICE EMCal, a large electromagnetic calorimeter, specifically tailored for the study of jets, electron, and photon production in proton-proton and Pb-Pb collisions. Professor Cormier now pursues the addition of a new calorimeter, the DCAL, based on technology identical to that of the EMCal, for the study of di-jet production.

The group welcomed, as of September 2011, the addition of a new member, Professor Joern Putschke, formerly from Yale University. Professor Putschke is a specialist in correlation functions and jet measurements in heavy ion collisions. Together with his colleagues, he pursues studies of jet production in p+p and Pb+Pb collisions in order to learn about medium transport properties. Members of the group also have interest in various aspects of the ALICE physics program ranging from flow measurements, measurements of two and three particle correlations, event-by-event fluctuations of the net charge, particle yield ratios, particle transverse momentum, and direct photon production to name just a few.

The group currently involves four post-doctoral students and research associates (Drs. Alexander Bourrisov, Alexandru Dobrin, Alexey Pavlinov, and Sidhard Prasad), and four Ph.D. students (Deeptanshu Jha, Vera Loggins, Jocelyn Mlynarz, and Chris Yaldo).

To learn more, visit the Relativistic Heavy Ion Group.