George Stephans, Academic Staff

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Area of Physics

Relativistic Heavy Ion Physics

Research Interests

Using collisions of atomic nuclei at extremely high speeds to study the properties of nuclear matter at very high temperature and density. 

These studies have included a long sequence of experiments over many years including:

• E802/859/866/917 at the AGS accelerator at Brookhaven National Lab
• Phobos at the RHIC collider at Brookhaven National Lab
• CMS at the LHC collider at CERN

The goal is to further our understanding of Quantum ChromoDynamics (QCD), the basic theory of the so-called strong interaction which binds protons and neutrons in nuclei, or to be more precise the interaction between quarks and gluons, the constituents of almost all sub-atomic particles. QCD theory had predicted the formation of a new state of matter, the Quark Gluon Plasma, at sufficiently high temperature or density. Experiments at RHIC, including Phobos, have verified the existence of this exotic matter but also revealed that many of its properties were very different from expectations.  Experiments at RHIC and the LHC are continuing the exploration of this novel and puzzling state of matter.

Biographical Sketch

George Stephans received his undergraduate degrees in Physics and Astronomy from the University of Pennsylvania in Philadelphia. After receiving a Masters degree in Physics from the University of Washington in Seattle, he returned to Penn and completed his Ph.D. in Nuclear Physics in 1982. After graduating from Penn, he first worked as a Postdoctoral Associate in the Physics Division at the Argonne National Laboratory outside of Chicago. He came to MIT as a Research Scientist in 1985 and has worked in the Relativistic Heavy Ion Group (formerly just the Heavy Ion Group) within the Laboratory for Nuclear Science. He is currently a Senior Research Scientist within LNS and a Senior lecturer within the Physics Department. In addition to his research participation, George has had an active involvement with teaching within the Physics Department, including helping to initially develop the 8.01L course (for which he shared the Buechner Prize) and later converting this course to TEAL format.

Selected Publications

• Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at sqrt(s) = 0.9 and 2.36 TeV (CMS Collab), J. High Energy Phys. 02, 041 (2010)
• High transverse momentum triggered correlations over a large pseudorapidity acceptance in   Au+Au collisions sqrt(s_NN) = 200 GeV (B.Alver, et al., Phobos collab), Phys. Rev. Lett. 104, 062301 (2010)
• System size dependence of cluster properties from two-particle angular correlations in Cu+Cu and Au+Au collisions sqrt(s_NN) = 200 GeV (B.Alver, et al., Phobos collab), Phys. Rev. C81, 024904 (2010)
• critRHIC: The RHIC low energy program (G. S. F. Stephans) J. Phys. G: Nucl. Part. Phys. 32, (2006) S447-S453.
• System size and centrality dependence of charged hadron transverse momentum spectra in Au+Au and Cu+Cu collisions at sqrt(s_NN) = 62.4 and 200 GeV (B.B.Back, et al., Phobos Collab), Phys. Rev. Lett. 96,
  (2006) 212301.
• The PHOBOS Perspective on Discoveries at RHIC (B. Back, et al., Phobos Collab), Nucl.  Phys. A 757, (2005) 28, BNL  73847-2005 Formal Report.
• Centrality dependence of charged hadron transverse momentum spectra in Au+Au collisions from sqrt(s_NN) = 62.4 to 200 GeV (B.B.Back, et al., Phobos Collab), Phys. Rev. Lett.  94, (2005) 082304.
• Energy Dependence of Particle Multiplicities in Central Au+Au Collisions (B. Back, et al., Phobos Collab) Phys. Rev. Lett. 88 (2002) 22302.
• Ratios of Charged Antiparticles to Particles Near Midrapidity in Au+Au Collisions at 130 GeV (B. Back, et al., Phobos Collab) Phys. Rev.  Lett. 87 (2001) 102301.
• Antilambda Production in Au+Au Collisions at 11.7A GeV/c (B. Back, et al., E917 Collab) Phys. Rev. Lett. 87 (2001) 242301.
• Charged particle multiplicity near mid-rapidity in central Au+Au collisions at sqrt(s_NN) = 56 and 130 GeV (B. Back, et al., Phobos Collab) Phys. Rev. Lett. 85 (2000) 3100.