A fundamental understanding of the nucleon-nucleon (NN) interaction is one of
the ultimate goals of nuclear and hadron physics. Apart from their intrinsic importance for the study of nuclear forces, NN elastic scattering data are necessary, for example, in the modelling of meson production and other nuclear reactions at intermediate energies.
Quantum chromodynamics, the theory of strong interactions, is not able to determine the NN interaction from first principles because of its non-perturbative
nature at intermediate energies (the coupling constants are too strong). Hence,
phenomenological approaches are necessary to describe the NN interaction. Partial wave analyses (PWA), such as the ones regularly performed by the SAID
(Scattering Analysis Interactive Dial-in) group, have proved to be truly invaluable
tools over many years for researchers in this area. These analyses rely on the
quantity and quality of the experimental measurements of various proton-proton
(pp) and proton-neutron (pn) scattering observables at different energies over the
full angular ranges.
The goal of many experiments conducted at Cooler Synchrotron (COSY) has been
to provide PWA with the precision measurements of NN observables that are
essential for these analyses. The experiments presented in this thesis have been
carried out within the ANKE collaboration at COSY-Jülich, Germany. Data were
obtained using polarised or unpolarised proton beams with kinetic energies from
0.8 GeV up to 2.8 GeV and unpolarised hydrogen or deuterium cluster-jet targets.
The detection system of the ANKE spectrometer is the ideal set-up for carrying
out refined measurements at the small scattering angles that had not previously
been investigated.
The thesis comprises the measurements of the analysing power Ay and differential
cross section in pp elastic scattering, and preliminary results for the
analysing power in the pn quasi-free elastic scattering. These new data close
an important gap in the NN database at scattering angles up to 30�° and energies up to 2.8 GeV.
The results obtained are compared to the predictions from the SAID PWA published in 2007 that were based on data from earlier experiments. The impact of
the present results is demonstrated by the significant changes in the low partial
waves of the updated SAID PWA, which includes the new ANKE measurements
as well as the existing global data
