München 2019 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 54: Poster

HK 54.14: Poster

Thursday, March 21, 2019, 16:30–19:00, Foyer Theresanium

Production of π⁰η pairs on nucleons and nuclei — •Vahe Sokhoyan for the A2 collaboration — Universität Mainz, Institut für Kernphysik

The A2 Collaboration performs a manifold research program using real photons in the Crystal Ball/TAPS experiment at the MAMI accelerator facility in Mainz. The experiments are carried out with high-intensity unpolarized, linearly or circularly polarized photon beams, and unpolarized or polarized targets. The Crystal Ball/TAPS setup provides almost complete coverage in solid angle and is well suited for the detection of multi-particle final states. In order to probe the internal structure of the nucleon, the spectrum of baryon resonances is studied via measurements of unpolarized cross-sections and various polarization observables in single and double meson photoproduction.

The new data presented in this poster provide the world’s best statistical accuracy in the energy range from threshold to E_γ = 1.45   GeV for the γ p → p π⁰η reaction. The results obtained for the unpolarized cross section and beam helicity asymmetry are compared with exisiting models. Moreover, the possible modifications of the D₃₃(1700) resonance in the nuclear medium were studied using the production of π⁰η pairs on heavier targets (carbon, aluminum, lead) and the beam helicity asymmetry has been extracted for these targets for the first time.