  The ATLAS experiment has observed 1995 Z boson candidates in data
corresponding to 0.15 inverse nb of integrated luminosity obtained in the 2011
LHC Pb+Pb run at sqrt(s_NN)=2.76 TeV. The Z bosons are reconstructed via
di-electron and di-muon decay channels, with a background contamination of less
than 3%. Results from the two channels are consistent and are combined. Within
the statistical and systematic uncertainties, the per-event Z boson yield is
proportional to the number of binary collisions estimated by the Glauber model.
The elliptic anisotropy of the azimuthal distribution of the Z boson with
respect to the event plane is found to be consistent with zero.
