A Study of the Reaction $\bar{p} p \to \bar{p} p \pi$ + $\pi^-$ at a Beam Momentum of 7.23-{GeV}/$c$

The experiment and the measurement system are described. The determination of the momentum of the incident antiproton and the automatic decision system based on the measured ionization density are discussed in somewhat more detail, because the author has been especially involved in these aspects of the experiment. The cross section for the anti ppπ+π- final state is determined from the experimental data, the validity of the symmetry with respect to charge conjugation is tested and the separation of the sample in two classes is discussed, one mainly produced by one pion exchange and the other by diffraction dissociation. The predictions of the OPE-model are compared with the experimental data for the reaction anti pp → Δ(1236)anti Δ(1236).