Polarization Observables in η and π Production Using a Polarized Target with the Crystal Ball/TAPS at MAMI

摘要

Recent experiments using the Crystal Ball/TAPS setup at the MAMI accelerator in Mainz, Germany, continue to study the properties and the excitation spectrum of the nucleon with meson photoproduction. Electromagnetic excitations of the proton and neutron are essential for understanding their isospin decomposition. The electromagnetic coupling of photons to protons is different than that to neutrons in certain states. Hence, a complete partial wave analysis (PWA) can assist in yielding more information about any reaction, but requires the determination of polarization observables. Polarization observables play a crucial role as they are essential in disentangling the contributing resonant and non-resonant amplitudes, whereas cross section data alone is not sufficient for separating broad overlapping resonances. Preliminary results of polarization observables of η, single, and double π production off a polarized neutron (dButanol) target will be shown with comparison to predictions of recent multipole analyses. These results will greatly increase the world database on pseudoscalar meson production on neutrons.