RESEARCH ON PHOTON PRODUCTION BY ELECTRON - POSITRON ANNIHILATION AT THE PETRA STORAGE RING

128 pp. (1984).
The production of photons, neutral pions and $\eta$ - mesons in multihadronic events is investigated with the JADE detector at the electron - positron storage ring PETRA.The production properties of photons are in good agreement with theore- tical expectations from fragmentation models and quantum electrodynamics. The energy spectra scale with the centre of mass energy. Photon multiplicities as well as the photonic energy fraction are measured.Neutral pions are reconstructed by their decay into two photons. The corresponding energy spectra show scaling and agree with those of charged pions in the covered range.$\eta$ - mesons are observed in the two photon mass spectrum. Their energy spectrum is softer than the spectra of other mesons. The study of $\eta$ - meson production in special event - and jet- topologies suggests enhanced production rates in gluon fragmentation.A comparison of all measured photon sources dem onstrates the dominant production of inclusive photons from decays of neutral pions.