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M. Klopf, D Moser, L Raffelt, C. Roick, H. Saul, J. Klenke, G. Konrad, P Lennert, W. Mach, B. Märkisch, U. Schmidt, T. Soldner, R Virot, H. Abele:
"PERKEO III - Measurement of the Proton Asymmetry";
Poster: 66th annual meeting of the Austrian Physical Society (ÖPG), Wien; 09-27-2016 - 09-29-2016.

The semi-leptonic decay of the free neutron is well described within the Standard Model of particle physics (SM). Measurements of observables in neutron decay allow testing the SM and models comprising physics beyond the SM.
The PERKEO III Collaboration performed a measurement of the proton asymmetry parameter C at the Institut Laue-Langenvin (Grenoble, France). The proton asymmetry describes the angular correlation between the momentum of the decay proton and the spin of the neutron. In the SM, the decay of the free neutron is covered within the framework of V-A theory. All neutron decay parameters, including the proton asymmetry, depend only on the ratio of axial-vector (g_A) to vector coupling constant (g_V). Deviations from SM expectations would give a hint on additional couplings such as scalar or tensor couplings.
On our poster we will present the measurement principle with the focus on systematic effects of the PERKEO III experiment, and give first estimates for the systematic corrections. Systematic effects are mainly caused by shape and magnitude of the magnetic and electric fields, the shape of the neutron beam and the limited size of the detectors.