Contact Information
Department of Physics525 Northwestern Avenue
West Lafayette, IN
47907-2036
Map and Directions
Telephone:
(765) 494-2970
Fax:
(765) 494-0706
Denes Molnar
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Assistant Professor of Physicsmolnar@purdue.eduOffice:Physics 248 Telephone:(765) 496-8310 Fax:(765) 494-0706 Personal Homepage |
M.S., Physics 1997 University of Bergen
Ph.D., Physics 2002 Columbia University
Research Interests
In short:
Properties of nuclear matter at extreme energy densities, physics of relativistic heavy-ion collisions and the quark-gluon plasma, transport theory.
Longer introduction:
The fundamental theory of nuclear forces (the strong interaction, in other words) is quantum chromodynamics (QCD). According to QCD, nuclear matter is composed of quarks and gluons. In the everyday world, quarks and gluons always appear in bound states called hadrons, such as the proton or the pion. However, at very high temperatures (~ 10^12 K) and/or densities (~10^19 g/cm^3) the theory predicts the existence of novel new phases of matter. One of these phases is a hot and dense plasma of quarks and gluons.
It is widely expected that the quark-gluon plasma (QGP) was abundant in the Early Universe, and affected its evolution during the first few microseconds after the Big Bang. However, energy densities in the Universe today are largely insufficient for this primordial plasma to exist, apart from perhaps supernovas or the core of very massive stellar objects (so-called quark stars). Luckily there is a unique, experimentally controllable way to try to re-create and study the QGP in a violent collision of two heavy ions.
In a collision of two very fast and large nuclei (relativistic gamma factors ~ 100, mass numbers ~ 200), a macroscopic portion of nuclear matter is compressed and heated up briefly to extreme temperatures (T ~ few x 10^12 K, lifetimes ~ 10^-24 seconds). The higher the collision energy, the higher the temperatures and densities reached are. As the hot and dense quark-gluon system expands, it cools rapidly and eventually transforms back to ordinary hadrons (hadronization). Heavy-ion experiments can detect only the hadrons in the final state, which makes it an exciting theoretical detective work to infer the plasma properties. Understanding the collision dynamics involves a combination of several physics disciplines, such as particle physics, nuclear physics, condensed matter physics, plasma physics, nonequilibrium phenomena, and nonlinear dynamics.
The current "best" collider facility (with highest collision energy) is the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Exciting recent data from gold-gold collisions at RHIC indicate the formation of extremely dense matter at 10-100 times normal nuclear density that appears thermalized and exhibits a remarkable ideal fluid behavior. Theoretical and experimental investigations are underway to confirm without doubt that the matter created is indeed the quark-gluon plasma and to extract further matter properties, such as the equation of state, viscosity, and diffusion constants. The findings will be tested and extended to higher temperatures at the next generation collider machine, the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland), that starts operation in 2007. Knowledge of the quark-gluon plasma properties will provide novel insights into the early history of our Universe and into the nature of the strong interaction.
Professional Experience
- Assistant Professor, Department of Physics, Purdue University, 2005-present
- Postdoctoral Researcher, Department of Physics, Ohio State University, 2003-2005
- Postdoctoral Fellow, Department of Physics, Ohio State University , 2002-2003.
Awards and Honors
- Department of Energy Office of Science Early Career Research Award, 2010
- RIKEN/BNL Fellowship 2005-present
- Ohio State University Postdoctoral Fellowship 2002-2003