Dresden 2013 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 73: Hadronenstruktur und -spektroskopie

HK 73.9: Vortrag

Donnerstag, 7. März 2013, 19:00–19:15, HSZ-105

Photoproduction of Pion-Pairs off Nucleons — •Markus Oberle — Departement of Physics, University of Basel, CH-4056 Basel, Switzerland

Photoproduction of meson pairs is an important tool for the investigation of nucleon resonances. At higher excitation energies many nucleon resonances have only small decay branching ratios to the nucleon ground state. They decay preferentially to intermediate excited states. This is similar to nuclear physics, only a very rudimentary picture of nuclear structure would arise when only ground-state transitions were considered. The experimental study of such decays requires the measurement of final states with at least meson pairs. The analysis of such reactions requires the measurement of differential cross sections and polarization observables.

The present experiment measured photoproduction of pion pairs (π⁰π⁰, π⁰π^± final states) off free protons and off quasi-free protons and neutrons bound in the deuteron at the MAMI accelerator in Mainz with the Crystal Ball/TAPS detector. Results for beam-helicity asymmetries and differential cross sections will be discussed and compared to the results from reaction models.