  The invariant yield of electrons from open-heavy-flavor decays for $1<p_T<8$
GeV/$c$ at midrapidity $|y|<0.35$ in Au$+$Au collisions at $\sqrt{s_{_{NN}}}$ =
200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy
Ion Collider. A displaced-vertex analysis with the PHENIX silicon-vertex
detector enables extraction of the fraction of charm and bottom hadron decays
and unfolding of the invariant yield of parent charm and bottom hadrons. The
nuclear-modification factors $R_{AA}$ for electrons from charm and bottom
hadron decays and heavy-flavor hadrons show both a centrality and a quark-mass
dependence, indicating suppression in the quark-gluon plasma produced in these
collisions that is medium sized and quark-mass dependent.
