The Influence of the Underlying Event on Jet Measurements in Heavy Ion Collisions

We present a study of the performance of jet reconstruction algorithms for Pb+Pb collisions at $sqrt{s_{NN}} = 5.52$~TeV/n based on a full GEANT simulation of the ATLAS detector. We show that ATLAS can provide measurements that are sensitive to different in-medium energy loss scenarios leading to the jet quenching. We present the capability of measurements of fragmentation function and $j_T$ distribution. We concentrate on some biases in these measurements that might be due to the detector effects or due to the choice of a jet finding algorithm.