P. Wüstner

ANKE, a new facility for medium energy hadron physics at COSY-Jülich

Abstract ANKE is a new experimental facility for the spectroscopy of products from proton-induced reactions on internal targets. It has recently been implemented in the accelerator ring of the cooler synchrotron COSY of the Forschungszentrum Julich (FZ-Julich), Germany. The device consists of three dipole magnets, various target installations and dedicated detection systems. It will enable a variety of hadron-physics experiments like meson production in elementary proton–nucleon processes and studies of medium modifications in proton–nucleus interactions.

Evidence for a narrow resonance at 1530MeV/c2 in the K0p-system of the reaction pp→Σ+K0p from the COSY-TOF experiment

The hadronic reaction pp -->Sigma+ K0 p was measured exclusively at a beam momentum of 2.95 GeV/c using the TOF detector at the COSY storage ring. A narrow peak was observed in the invariant mass spectrum of the K0 p subsystem at 1530 +- 5 MeV/c2 with a significance of 4 - 6 standard deviations, depending on background assumptions. The upper limit of 18 +- 4 MeV/c2 (FWHM) for its width is given by the experimental resolution. The corresponding total cross section is estimated to be about 0.4 +- 0.1(stat) +- 0.1(syst) microbarn. Since a resonance in this subsystem must have strangeness S = + 1 we claim it to be the Theta+ state for which very recently evidence was found in various experiments.

COSY- 11, an internal experimental facility for threshold measurements

Abstract The COSY-11 installation is an internal experiment at the cooler synchrotron and storage ring COSY Julich. It has been designed for full geometrical acceptance close to threshold for meson production studies, especially in the 1 GeV/ c 2 mass range. The experimental setup makes use of a regular C-type COSY dipole magnet, following a cluster target, to separate reaction products from the beam and to analyze their momenta, thus allowing the observation of charged reaction products at small angles with beam energies close to threshold. Resonances will be identified by missing mass reconstructions from measured four-momenta of two outgoing protons in the predominantly studied pp → ppX reaction. In addition, charged mesons either produced directly or from decays of X will be detected. The different components of the experimental facility are presented.

ETA ' PRODUCTION IN PROTON-PROTON SCATTERING CLOSE TO THRESHOLD

The

S-wave η′-proton FSI; phenomenological analysis of near-threshold production of π0, η, and η′ mesons in proton-proton collisions

pp \to pp \eta^{\prime}

Near-threshold η meson production in proton-proton collisions

(958) reaction has been measured at COSY using the internal beam and the COSY-11 facility. The total cross sections at the four different excess energies \mbox{

Comparison of Lambda and Sigma**0 threshold production in proton proton collisions

Q = ~1.5 ~MeV, ~1.7 ~MeV, ~2.9 ~MeV,

Energy dependence of the near-threshold total cross-section for the pp→ppη′ reaction

and

Experimental study of pp eta dynamics in the pp ---> pp eta reaction

~4.1 MeV

Λ-hyperon production via the pp → pK+Λ reaction 2 MeV above threshold

} have been evaluated to be \mbox{