Welcome to the website for the Nuclear Physics Group at the University of Colorado. You can contact us directly in our laboratory Duane E116 at 303-735-2996 or email jamie.nagle@colorado.edu

Professors Ed Kinney, Jamie Nagle, Jerry Peterson

The Quark-Gluon Plasma in Heavy Ion Collisions


What Have We Learned From the Relativistic Heavy Ion Collider? in Physics Today, October 2003.
   The quark-gluon plasma (QGP) is a state of matter in which partons are no longer contained within the normal hadronic states, but rather are deconfined due to the extremely high energy density and temperature of the plasma. To achieve the necessary energy density, we collide heavy ions (such as gold and copper) at 200GeV CM energy per nucleon pair using the Relativistic Heavy Ion Collider at Brookhaven National Laboratory on Long Island. We are interested in several predicted signatures (and corresponding properties) of the QGP, including J/Psi suppression (color-charge Debye screening), jet suppression and modification (energy loss), hydrodynamic flow and collective motion (viscosity), and heavy flavor production (thermalization).


Spin Structure of the Proton

 In the naive parton model, a proton consists of two up quarks and a single down quark. With the proton having a total spin of 1/2, the simple expectation would be that two of the quarks have their spin aligned along the proton's spin and the remaining quark has its aligned opposite. Data taken in the 1980's and 1990's showed that only ~15% of the proton's spin was carried by the quarks. The remainder of the spin is expected to be carried in the gluons' spin and the orbital angular momentum of the quarks and gluons. The measurment of the gluon component of the proton's spin is our primary concern. It remains poorly constrained by existing data from polarized deep inelastic scattering. We measure spin asymmetries in polarized proton-proton collisions, which are sensitive to the gluonic contribution, at the Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Lab to gain access to this important piece of the proton's spin.