Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 12: Poster Session: Instrumentation and Applications
HK 12.26: Poster
Tuesday, March 9, 2004, 13:30–15:30, Foyer
The spectrometer aSPECT - A Superconducting Spectrometer to analyze the Fundamental Laws of Weak Interaction in Neutron Beta Decay — •Stefan Baeßler1, Jim Byrne2, Ferenc Glück1, Joachim Hartmann3, Werner Heil1, Igor Konorov3, Raquel Muñoz Horta1, Marius Orlowski1, Gerd Petzoldt1, Yuri Sobolev1, Maurits van der Grinten2, and Oliver Zimmer3 — 1Institut für Physik, U. Mainz — 2University of Sussex, Falmer, Brighton, UK — 3Physik Department E18, TU München
Since recently the upper left element of the Cabbibo-Kobayashi- Maskawa-Matrix Vud can be determined from neutron decay data alone with an accuracy which is comparable to the traditional derivation from nuclear decay data. Both methods agree with each other. However, both values for Vud, together with Vus and Vub from high energy physics, violate the unitarity of the Cabbibo-Kobayashi-Maskawa-Matrix by about 2 to 3 sigma. The neutron decay data used for this test is the neutron lifetime τn and the beta asymmetry A. Recent determinations of A are not consistent with each other. In the Standard Model, measurements of the neutrino electron correlation coefficient a are equivalent to measurements of A, so that a new measurement of a can either solve the unitarity problem, or it can confirm it with entirely different systematics. In this poster the spectrometer aSPECT is presented. Its purpose is to measure a with a relative accuracy of a few parts per thousand which corresponds to an improvement in A by half an order of magnitude.