Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 74: Fundamental Symmetries
HK 74.1: Gruppenbericht
Donnerstag, 19. März 2009, 16:30–17:00, H-ZO 70
aSPECT - Measuring the proton spectrum in neutron decay — •Martin Simson1,2, Fidel Ayala Guardia3, Stefan Baeßler4, Michael Borg3, Ferenc Glück5, Werner Heil3, Igor Konorov2, Gertrud Konrad3, Raquel Muñoz Horta3, Kent Leung1,2, Yury Sobolev3, Torsten Soldner1, Hans-Friedrich Wirth6, and Oliver Zimmer1,2 — 1Institut Laue-Langevin, Grenoble, France — 2Physik-Department E18, TU München — 3Institut für Physik, Universität Mainz — 4University of Virginia, Charlottesville, VA, USA — 5IEKP, Universität Karlsruhe (TH) — 6Fakultät für Physik, LMU München
With the aSPECT spectrometer we measure the proton recoil spectrum in the decay of the free neutron. Its shape depends on the angular correlation between the momenta of the antineutrino and electron for kinematic reasons. A precision measurement of this correlation coefficient a allows to test the unitarity of the CKM matrix and provides limits on the existence of scalar and tensor currents.
aSPECT is a retardation spectrometer, i.e. the proton recoil spectrum is measured by counting all decay protons that overcome a potential barrier. By varying the height of the barrier the shape of the proton spectrum can be reconstructed. After the barrier the protons are accelerated to ∼15 keV and detected by a silicon drift detector.
In the last beam time a statistical accuracy of about 2 % per 24 hours measurement time was reached, the total error is expected to be well below 5 %. Details of the spectrometer setup as well as the status of the ongoing data analysis will be presented in the talk.