Di-jet Shape Modification in Heavy Ion Collisions

We present preliminary results from intermediate $p_T$ (1-5 GeV/c) di-hadron azimuthal correlations induced by hadronic di-jets produced in $AuAu$ collisions at $\sqrt{s_{NN}} = 200 GeV$. The near side ($\Delta\phi\sim 0$) has a typical single-peaked structure which broadens with the centrality of the collision. A qualitatively new phenomenon shows up in the shape of the away side ($\Delta\phi\sim\pi$): it has a symmetric, double-peaked structure in central and mid-central collisions.