First internal and external experiments at COSY Juelich

The inauguration of the cooler synchrotron COSY Jülich was celebrated on April 1st, 1993. After the first successful acceleration to proton momenta above 800 GeV/c, beamtimes for experiments were scheduled in parallel to further machine development. The first experiment was the internal target experiment EDDA, which investigated the energy dependence of the p-p interaction. It makes use of a 3 × 4 μm2 thin CH2 fiber as an internal target. The thickness of the fiber is more than adequate to achieve high luminosities, so the intensity of the stored beam has to be reduced to 107 p. On the other hand, it is thin enough to achieve beam lifetimes of 3 s at 1.4 GeV/c. Details of the target fabrication and the first experimental results will be discussed. xternal experimental facilities at COSY, the time-of-flight spectrometer, and the magnetic spectrometer BIG KARL use a liquid hydrogen (deuterium) target. The first experiments were carried out at proton energies between 300 MeV and 500 MeV. Also, these experimental data will be presented. rther internal experiments are prepared for the installation into the COSY ring. The target for the first experiment is a gas-jet target, the second experiment uses ribbon targets for the interaction. The status of both experimental setups will be shown.