K+p Interactions at 10 GeV/c, and, Polly - A Film Measuring Machine

This thesis contains the work of the author on an experiment to study the interactions of positive K-mesons with protons at an incident laboratory momentum of 10 GeV/c. It also includes a description of the author's work in implementing a computer controlled bubble chamber film measuring device, Polly, at Glasgow University. A brief survey of current theoretical ideas relevant to the following work on high energy physics is given in Chapter I. Chapter II describes the experiment, which was a Birmingham-Glasgow-Oxford collaboration using the CERN Proton Synchrotron and 2 metre hydrogen bubble chamber. The Glasgow bubble chamber group system of analysis programmes is summarised, and the measurement and analysis of the events in which six charged particles were produced is described. The results of a spin-parity analysis of the I=1/2 low mass baryon system formed in four prong events are shown in Chapter III. These indicate that spin-parities 3/2 and 5/2 states are present, but no evidence for states with a A( 1236)pi decay mode was obtained. Chapter IV is based on the observation of an I=3/2 baryon resonance at 1.9 GeV/c2 in the four and five body final states. The branching ratios of this resonance are evaluated, and are compared with results obtained from other experiments. The theory of single particle momentum distributions has received attention recently: the momentum distributions for negative pions and neutral kaons produced in the experiment are presented in Chapter V, and compared with published data at different beam momenta. The results indicate that the scaling behaviour of the centre-of-mass longitudinal momentum with centre-of-mass energy is not observed in K+p interactions at around 10 GeV/c incident momentum, although further data from other experiments will be required before this can be definitely established. The remaining two chapters deal with the aspects of the computer controlled film measuring device, Polly, which have concerned the author. The extraction of bubble density information from the Polly data is treated in depth, and, although at the time of writing Polly had not reached the production stage, the predictions of the derived equations are shown to agree with the Polly data available. The appendix to this thesis explains the amplitude terms used in the analysis in Chapter III