Speaker
Manuel Dieterle
(Basel University, Department of Physics)
Description
Meson photoproduction allows a detailed investigation of the excitation spectrum of the nucleon and of the interactions of mesons with nucleons and nuclei. Up to now much more attention has been paid to the electromagnetic excitations of the free proton than to its neutron counter parts. These are essential for the understanding of their isospin decomposition. In addition in certain states the electromagnetic coupling of photons to protons is rather different from that to neutrons. So far the sole experimental possibility to investigate this subject is the quasi-free photoproduction of mesons off neutrons bound in nuclei, in particular in the deuteron. As a consequence the production cross section will of course be influenced by nuclear Fermi motion and potentially also by nuclear final state interaction effects (FSI). However, such effects can be studied by a comparison of the free proton cross section to the quasi-free cross section measured in coincidence with recoil protons.
In the last few years, the photoproduction of mesons off the deuteron were studied with the Crystal Barrel/TAPS setup at the ELSA accelerator in Bonn and the Crystal Ball/TAPS setup at the MAMI accelerator in Mainz. We will report some of the most interesting results of single and double pion photoproduction, i.e. $\pi^{0}$, $\pi^{0}\pi^{0}$, $\pi^{0}\pi^{\pm}$, off quasi-free protons and neutrons.
Primary author
Manuel Dieterle
(Basel University, Department of Physics)
