About Us

The research of the High Energy Nuclear Physics Group focuses on the exploration of the equation of state of nuclear matter. The Purdue High Energy Nuclear Physics Group is in the forefront of this exciting area of research.

The goal is the creation and observation of highly excited and unusual states of nuclear matter. Traditional nuclear physics has been devoted to the study of nuclei which are gently perturbed. Using high energy beams of heavy nuclei, we can create states of nuclear matter that are far removed from the ground state. For example, at sufficiently high densities and temperatures, neutrons and protons should "melt" into their constituent quarks, forming the so-called quark-gluon plasma. The quark-gluon plasma state is predicted to have existed some microseconds after the Big Bang. Understanding nuclear matter under these extreme conditions will provide fundamental information about Nature.

We search for the quark-gluon plasma in experiments conducted at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory (BNL). Heavy-ion beams are accelerated to a speed 99.995% of the speed of light. A collision of these beams produces thousands of particles (hadrons). We measure those particles with the STAR experiment. This experiment is at data taking stage. We are presently analyzing data from the experiment.

Particularly challenging is the development of unambiguous signals for phase transitions in very small systems where the number of constituents is in the hundreds. The Purdue Group is studying the liquid-gas phase transition in finite nuclei and has identified unambiguous signals of a critical point which is analogous to the signatures in extended matter. The understanding of this phase transition will provide guidance in the search for the quark-gluon plasma.

Besides the experimental group, we also have a High Energy Nuclear Theory Group led by Professor Denes Molnar. The interactions of particles (hadrons) produced in relativistic heavy-ion collisions are governed by Quantum Chromodynamics, the fundamental theory of the strong interaction. The large number of particles produced in each collision also makes it possible to use macroscopic description and hydrodynamics. The theory group provides critical inputs to the interpretation of experimental data using Quantum Chromodynamics as well as hydrodynamics.

For inquiries regarding the High Energy Nuclear Physics Group send mail to Dr. Andy Hirsch at hirsch@physics.purdue.edu