Berlin 2005 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 6: Kern- und Teilchen-Astrophysik

HK 6.5: Vortrag

Freitag, 4. März 2005, 15:15–15:30, TU MA144

The Electron Asymmetry A in the Decay of free neutrons — •Daniela Mund¹, Hartmut Abele¹, Stefan Baeßler², Markus Brehm¹, Jochen Krempel¹, Michael Kreuz^1,3, Bastian Märkisch¹, Alexander Petoukhov³, Marc Schuman¹, and Torsten Soldner² — ¹Physikalisches Institut Universität Heidelberg — ²Institut für Physik Universität Mainz — ³Institut Laue-Langevin (ILL)

We measured the β-asymmetry A, the correlation between the neutron spin and the electron momentum, in the decay of free polarized neutrons. From A and the neutron lifetime τ, you can derive the first element of the quark mixing CKM matrix, V_ud. Previous experimental values on V_ud and V_us violate the unitarity condition of the first row of this matrix. Hence we seek for clarification with this measurement.

Our spectrometer PERKEOII was placed at the ILL at the cold neutron beam PF1B. We improved our setup in systematics, like polarisation, background and detector function, and in statistics. We will report about our experiment and its results.