The PHENIX experiment has measured midrapidity transverse momentum spectra (0:4NN= 200GeV.Contributions from photon conversions and Dalitz decays of light neutral mesons are measured by introducing a thin (1.7%X₀) converter into the PHENIX acceptance and are statistically removed. The subtracted nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons containing heavy quarks, mainly charm at lower pτ. For all centralities, the charm production crosssection is found to scale with the nuclear overlap function,T_AA. For minimum-bias collisions the charmcross section per binary collision isN_cc=T_AA622±57(stat)±160(syst)μb