Search

The work reported in this thesis covers the latter part of a programme undertaken at A.E.R.E. Harwell to collect data on the nucleon-nucleon scattering problem at energies accessible to the Harwell 280 cm synchrocyclotron. The experiments described belong to the second phase of data collection at these energies in that they do not of themselves determine a unique set of phase shifts in a modified phase-shift analysis, but resolve ambiguities in the earlier data available, or improve the precision to a significant degree. The first chapter contains a review of the nucleon-nucleon scattering problem, and provides a common context for the different types of experiment described. The second chapter is devoted to a description of the development and final form of a polarised proton target for use in the 70-150 Mev region for proton-proton scattering. Radiation damage resulted in a decay of the polarisation produced in this target, and a brief study of this phenomenon (described in Chapter II) was required to supplement the polarisation decay data collected in the spin correlation experiment reported in the third chapter. The third and fourth chapters contain the experimental method and analysis of experiments using the polarised target to determine the spin correlation parameter Cnn in proton-proton scattering at 90° centre of mass for three energies: 74, 98, and 143 Mev; and at 61.8° centre of mass at 143 Mev only. A typical precision of ± 0.05 was obtained for this parameter. The fifth chapter contains a description of the apparatus and methods used for measurements of polarisation in the 98 Mev region: the experiment at 98 Mev to determine P(θ) in p-p scattering is described and analysed in chapter six. Due to a recent remeasurement of the polarisation of the Harwell 142 Mev polarised proton beam, absolute polarisation values were obtained, to a typical precision of ± 2% of the peak value of the asymmetry. The 98 Mev data provide a notably more stringent restriction on phase-shift fits at this energy than previous polarisation information. The preliminary results of a measurement of the absolute differential cross section for p-p scattering at 98.8 Mev are briefly discussed, and the chapter concluded with a compilation of the N-N scattering data now available in the energy range 60-160 Mev.