At the Cooler Synchrotron COSY in Jülich the production of
strange particles has successfully been measured.
At the internal COSY-11 experiment  a hydrogen cluster target is
installed in front of a regular COSY-dipole.
This magnet is used as a spectrometer for the reaction products.
The detection system is based on drift chambers and
Near threshold data of the pp->pK+Lambda reaction have recently been published by the COSY-11 [2-4] and the COSY-TOF collaboration . Since before these COSY-measurements no exclusive data in the threshold region were available, the present results have given input to theoretical models describing the strangeness production in baryon-baryon collisions. Investigations of the hyperon-production above the different Sigma-thresholds provides an understanding of the Sigma-production processes and of the possible Lambda-Sigma coupling (cusp-effect).
Therefore the COSY-11 collaboration has extended its program from the Lambda- to the Sigma0-production. After the presentation of the COSY-11 facility the results of the pp->pK+Sigma0 measurements  will be compared to the pp->pK+Lambda reaction. It was found, that the corresponding cross sections at equivalent excess energies near threshold are about a factor of 28 smaller for the Sigma0-production than for the Lambda-production.
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Publication: Nucl.Phys. A 663-664 (2000) 473-476