  The production of electron pairs with transverse momentum between 1 and 5
GeV/c and m< 300 MeV has been measured at mid-rapidity in 200 GeV p+p and Au+Au
collisions by the PHENIX experiment at RHIC. A significant excess above the
hadronic background was observed in both p+p and Au+Au collisions. Treating the
excess as internal conversion of direct photons, the direct photon yield in
Au+Au was found to be enhanced compared to the binary-scaled p+p yield. The
enhancement is consistent with an exponential inverse slope of 221 +- 23 +- 18
MeV and predictions from hydrodynamical models with initial temperature between
300 and 600 MeV at formation times of 0.6-0.15 fm/c.
