The in-medium properties of the omega meson were investigated at the MAMI-C electron accelerator using the Crystal Ball/TAPS detector system to identify omega mesons through their omega -> pi(0)gamma decay channel. Two solid targets (C, Nb) and a LH2 target as a reference have been used. In the energy range 900 to 1300 MeV the omega lineshapes for the different nuclei are compared and a broadening of the omega signal for the niobium target is observed in comparison to the liquid-hydrogen target. In a second analysis the omega momentum distributions for the solid targets are determined for 50 MeV/c wide bins. For both analyses a comparison to transport calculations shows that the data are consistent with an in-medium modification by collisional broadening, as observed by transparency ratio measurements.
- PHOTON SPECTROMETER TAPS
- PROTON-NUCLEUS REACTIONS