Suppression of high transverse momentum charged hadrons in Au+Au collisions at 200 GeV nucleon-nucleon center of mass energy

The dynamical properties of quark gluon plasma are studied in heavy ion collisions. Gold ions are accelerated with the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and collided at energies up to 200 GeV per nucleon. Collision products and their properties are detected and measured with the PHENIX detector. At these energies the colliding ions may form a thermalized distribution of quarks and gluons called the Quark-Gluon Plasma. The suppression of single hadrons still provides one of the strongest constraints on energy loss mechanisms in the Quark-Gluon Plasma. Presently, neutral pions provide the best measurement at RHIC of single particle suppression. Charged hadrons have independent sources of systematic uncertainty and can thus provide additional constraints. Background from off-vertex sources such as photon conversions and weak decays, which mimic high pT particles, have limited the measurement of charged hadrons to pT < 10 GeV/c at PHENIX. The newly installed silicon vertex tracker upgrade (VTX) can reject this background allowing the measurement of the charged hadron spectrum out to a significantly higher momentum, up to 26 GeV/c. The VTX is capable of performing precision measurements of the distance of closest approach of a track to the primary vertex (DCA). Off-vertex photon conversions and weak decays are vetoed with the VTX by rejecting tracks with large DCA.