  Energy-loss studies of hard particle probes produced in heavy ion collisions
have often been used to get information on the interactions within the medium
of a quark-gluon plasma (QGP). However, with the study of in-medium energy-loss
of individual particles alone, it remains still ambiguous, whether the occured
decrease in particle energy is caused by predominantly radiative or collisional
energy-loss mechanisms. Focusing on the in-medium energy-loss of hard
jet-partons, we propose additional studies of the angular jet-structure as a
means to further constrain the energy-loss mechanisms.
