  We present a measurement of dijet asymmetry and dijet azimuthal correlations
in Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV using the ATLAS detector.
This measurement provides the first evidence of a strong jet quenching in
relativistic heavy ion collisions at TeV energies. The jet reconstruction
procedure is discussed as well as studies which have been performed to check
that the observed asymmetry is not produced by detector effects and underlying
event backgrounds.
