Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 17: Hadronenstruktur und -spektroskopie V
HK 17.4: Vortrag
Dienstag, 22. März 2011, 15:00–15:15, C-2
Measurement of the photon asymmetry in neutral pion production from the proton near threshold — •Duncan Middleton — Institut für Kernphysik, Universität Mainz, J.J. Becher Weg 45, 55128, Mainz
The study of neutral pion prioduction off the proton close to threshold is a good tool for testing chiral perturbation theory. For this a precise determination of the S-wave and all three P-wave amplitudes which describe the process is necessary. This separation can be achieved using linearly polarised photons in addition to determining the total and differential cross sections for the reaction. Here we report on a measurement of γ→p→π0p reaction in the threshold region.
The measurement was performed in the A2 hall of the Mainzer Mikrotron MAMI. An 855 MeV electron beam impinged upon a 100 µm diamond radiator to produce a beam of linearly polarised photons in the range 100≤ Eγ≤200 MeV which were incident on a liquid hydrogen target. The recoil electrons from the Brehmsstralung process were detected in the Glasgow tagger of the A2 hall and the π0 decay photons in the Crystal Ball and TAPS detector systems.
Cross sections and beam asymmetries for the reaction γ→p→π0p will be shown. The data are compared to predictions of the MAID and SAID partial wave analyses and calculations based on chiral perturbation theory.