A STUDY OF THE NUCLEON-DELTA INTERACTION USING PION-INDUCED DEUTERON BREAKUP

This thesis reports the results of a kinematically complete experiment designed to study the reaction $\pi\sp{+}$ d $\to\pi\sp{+}$ p n in a range of phase space accessible to the high energy pion channel at LAMPF. (The Los Alamos Meson Physics Facility, a part of the Los Alamos National Laboratory in New Mexico.) The kinematics were chosen to emphasize the reaction $\pi\sp{+}$ d $\to\Delta\sp{++}$ n, where the subsequent decay of the delta particle produces the observed final state. At $\Delta\sp{++}$ production angles of 55$\sp\circ$ and 91$\sp\circ$ in the reaction center of mass frame of reference, differential cross sections were measured at seven beam momenta between 312 MeV/c (corresponding to $\sqrt{\rm s}$ = 2.19 GeV) and 600 MeV/c ($\sqrt{\rm s}$ = 2.42 GeV). At beam momenta of 350 MeV/c and 425 MeV/c, data were taken at seven center of mass $\Delta\sp{++}$ production angles between 30$\sp\circ$ and 120$\sp\circ$. These excitation functions and angular distributions will provide tests for various theoretical approaches to understanding the nucleon-delta interaction. In particular, these data are well fit by a conventional relativistic Faddeev theory using no free parameters. Over most of the phase space, both the shape of the momentum spectra and the magnitude of the cross sections are reproduced by the model. In regions near the peak of the $\Delta\sp{++}$ mass distribution, but far from the quasi-free scattering peak, this model underestimates the data by a factor which increases with energy. This factor does not appear to depend on the $\Delta\sp{++}$ production angle. Some possible explanations of the discrepancy are explored