  The suppression of high transverse momentum (P_T) inclusive hadron spectra in
heavy-ion collisions as compared to the scaled expectation of high P_T hadron
production in p-p collisions is the most direct manifestation of the
interaction of hard partons with the soft bulk medium produced in heavy-ion
collisions which is absent in p-p collisions. Yet the measured nuclear
suppression factor R_AA is a very averaged quantity and hence only a limited
amount of information about the medium evolution and the nature of the
interaction with the medium can be deduced from R_AA. Measurements of hard
back-to-back hadron correlations in 200 AGeV Au-Au collisions at RHIC have
opened a new window to study the energy loss of partons in a medium in a more
differential way and for a different distribution of in-medium pathlengths than
in the case of R_AA. In this work, we present an extrapolation of our results
for back-to-back yields at RHIC energies to 5.5 TeV Pb-Pb collisions at the
CERN LHC. We also discuss differences and similarities between the measurement
at RHIC.
