  Jet production in relativistic heavy ion collisions is studied using Pb+Pb
collisions at a center of mass energy of 2.76 TeV per nucleon. The measurements
reported here utilize data collected with the ATLAS detector at the LHC from
the 2010 Pb ion run corresponding to a total integrated luminosity of 7 inverse
microbarns. The results are obtained using fully reconstructed jets using the
anti-kt algorithm with a per-event background subtraction procedure. A
centrality-dependent modification of the dijet asymmetry distribution is
observed, which indicates a higher rate of asymmetric dijet pairs in central
collisions relative to peripheral and pp collisions. Simultaneously the dijet
angular correlations show almost no centrality dependence. These results
provide the first direct observation of jet quenching. Measurements of the
single inclusive jet spectrum, measured with jet radius parameters R =
0.2,0.3,0.4 and 0.5, are also presented. The spectra are unfolded to correct
for the finite energy resolution introduced by both detector effects and
underlying event fluctuations. Single jet production, through the
central-to-peripheral ratio RCP, is found to be suppressed in central
collisions by approximately a factor of two, nearly independent of the jet pT.
The RCP is found to have a small but significant increase with increasing R,
which may relate directly to aspects of radiative energy loss.
