Contribution to the experimental study of charmed hadrons produced with hyperon beams (WA89 experiment)

Since 1989 the author has been involved in the CERN WA89 experiment that is dedicated to the production of charmed hadrons with hyperon beams. The features and the experimental setting of WA89 are presented in the first chapter. The second chapter is dedicated to the on-line and off-line identification of Λ0 particles produced in charmed particles decay. The former is made through an adequate trigger and the latter is an event filter based on a fast identification criterion of a likely decay of Λ0. The identification of Λ0 has required the development of algorithms to test the validity of the track reconstruction in the decay area between the target and the spectrometer and to check the validity of the identification of the decay vertex of Λ0. The last chapter is dedicated to data analysis. The identification of DS mesons in K+K-π final state is detailed. An accurate determination of the DS production cross-section is not yet possible because of the low statistics but it was possible to make a preliminary assessment that has given: σ = (1.5 ± 0.7) μb/nucleon with xF > 0. (A.C.)