  Heavy quarks are good probes of the hot and dense medium created in
relativistic heavy ion collisions since they are mainly generated early in the
collision and interact with the medium in all collision stages. In addition,
heavy flavor quarkonia production is thought to be uniquely sensitive to the
deconfined medium of the Quark Gluon Plasma (QGP) through color screening.
Heavy quark production has been studied by the PHENIX experiment at RHIC via
measurements of single leptons from semi-leptonic decays, in both the electron
channel at mid-rapidity and in the muon channel at forward rapidity. Large
suppression and azimuthal anisotropy of single electrons have been observed in
Au+Au collisions at 200 GeV. These results suggest a large energy loss and
strong flow of the heavy quarks in the hot, dense matter. The PHENIX experiment
has also measured J/psi production in p + p, d+Au, Cu+Cu, and Au+Au collisions
at energies up to 200 GeV. In central Au+Au at 200 GeV, more suppression is
observed at forward rapidity than at central rapidity. This can be interpreted
either as a sign of quark recombination, or as a hint of additional cold
nuclear matter effects. Selected PHENIX results on open heavy flavor and heavy
quarkonia production in p + p, d+Au, Cu+Cu, and Au+Au collisions are presented.
The status of the recent PHENIX upgrade of the central Silicon Vertex Tracker
(VTX) and its performance are elucidated.
