Production of neutral pions and high-energetic photons in collisions of light and medium-heavy nuclei at 44 and 48 MeV/u

In this thesis about experiments on the production of neutral pions and high-energetic photons in nulceus-nucleus collisions at 44 and 48 MeV/u is reported. The main aim was the determination of the mass dependence in the π0 production in order to obtain informations about the number of the nucleons contributing to the production process. Furthermore the hitherto known excitation function should be extended to lower energy in order to make the comparison with the theoretical models more sensitive. For the detection a double ring of lead-glass Cherenkov counters was used which posesses a large detection probability for neutral pions of 0-400 MeV/c over the whole angular range and is on the other hand very insensitive against the background by other reaction products. It allows measurements of the π0 production cross section until below 50 pb/(sr MeV). The experiments were performed at the CERN synchrocyclotron and the cyclotron of GANIL with 12C, 20Ne, 40Ar, and 86Kr projectiles. Targets of 12C, Mg, 40Ca, Zr, Sn, 181Ta, and 238U were irradiated whereby the special interest was aimed each to the symmetric systems because these are best suited to study the mass dependence of the pion production. (orig./HSI)