| It has been believed for over 30 years that matter will become a deconfined state of quarks and.;gluons at sufficiently high energy densities. As the energy density increases, deconfinement occurs.;due to Debye screening of the color charges, which disrupts the binding of mesons and baryons. The.;expected deconfinement transition to quark-gluon plasma (QGP) has been observed using collisions.;of heavy ions to create high energy densities,first at the Relativistic Heavy Ion Collider (RHIC).;at Brookhaven National Laboratory, and more recently at the Large Hadron Collider (LHC) at.;European Organization for Nuclear Research (CERN).;The degree to which the binding of a hadron in the plasma is disrupted depends on its radius.;Because deconfinement is caused by Debye screening, and the screening length is determined by.;energy density, small tightly bound heavy quark mesons (referred to as quarkonia) may become.;deconfined at a higher energy density than the light quark hadrons. Thus, measuring quarkonia.;production may provide a way to determine the screening length in the QGP, and a program of.;measurements of modification of charmonium and bottomonium states in heavy ion collisions has.;been carried out at several accelerators over the last two decades.;As part of this effort, measurements of J/psi production in Au+Au collisions have been made by the.;PHENIX experiment at RHIC, the subject of this thesis. Specifically, J/psi --> e+e- data from.;Sqrt(sNN) = 200 GeV Au+Au collisions were recorded in 2004, providing the first major quarkonia result from PHENIX. A higher statistics measurement was performed in 2007, but a non-functioning detector.;subsystem in the PHENIX central arms rendered the data unusable. A still larger data set was.;recorded 2010, this time with the previously non-functioning detector system working. It is these.;2010 data that are the focus of the present analysis.;The 2010 dataset contains about 5 times as many measured J/psi as the 2004 dataset. However.;the increase in signal is accompanied by a large increase in background electrons, which introduces.;difficulties not present in the 2004 analysis. The goal of this analysis was to improve on the result.;from the 2004 measurement. |
