Multiplicities in phase space intervals and Bose-Einstein correlations in hadronic interactions at 250 GeV/c

This thesis describes a number of aspects of multiparticle production in π+p, K+p and pp collisions at an incident beam momentum of 250 GeV/c. The corresponding centre of mass energy is 21.7 GeV. The experimental data have been collected with the European Hybrid Spectrometer at CERN. The experimental set-up and data processing chain are described in chapter 2. Chapter 3 concerns the methods used for the charged particle identification in the experiment. The analysis of the properties of the particle collisions starts in chapter 4. Here, a study of the multiplicity distribution in phase space intervals is presented. This analysis is done for the non-single-diffractive π+p and pp collisions. In general the data can be well described by negative binomial distributions. This holds in particular for central regions of rapidity. However, also indication is seen for the existence of correlations in the data beyond those already absorbed into negative binomials. It is shown that the interpretation of the negative binominal distribution in terms of a cascading rather than the stimulated emission mechanism is favoured. The data are, furthermore, compared with results at other energies and another type of collision. As a consequence of the requirement of a symmetric wave function for identical pions, the probability for two identical pions to be close in phase space is enhanced compared to what is expected for non-identical particles under the same conditions. These Bose-Einstein correlations are studied in chapter 5 for the combined π+p and K+p sample. In particular, the interference effect has been studied with different reference samples and with different parametrisations of the effect. 108 refs.; 57 figs.; 23 tabs