Mainz 2004 – wissenschaftliches Programm
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T: Teilchenphysik
T 605: Vermischtes
T 605.9: Vortrag
Donnerstag, 1. April 2004, 12:30–12:45, HS VI
A superconducting magnetic UCN trap for precise neutron lifetime measurements — •Johannes Bröcker, Igor Altarev, F. Joachim Hartmann, Andreas Frei, Andreas Gschrey, Erwin Gutsmiedl, Rüdiger Picker, Stephan Paul, Gerd Petzoldt, Wolfgang Schott, Daniele Tortorella, and Oliver Zimmer — Physik-Department E18, Technische Universität München
The measurement of the neutron lifetime τn allows to precisely determine the coupling constants of weak interaction and hence the element Vud of the CKM matrix. Latest experimental results indicate that this matrix deviates from unitarity by about 3 σ. The most precise measurements of τn were performed by storing ultra-cold neutrons (UCN) in material bottles. There are, however, significant losses during wall collisions that are not fully understood. Hence systematical errors cannot be decreased substantially below their present values.
Recently it was proven that magnetic storage is a viable alternative. In our planned experimental arrangement the volume between two nested cylinders made from magnetic multipole fields is used to store UCN. The field is produced by superconducting coils with gravitation serving as the upper lid of the bottle. τn shall be measured by real-time detection of decay protons and by counting the integral number of neutrons left after different storage times. Using a new UCN source we expect to trap up to 108 neutrons per cycle. We thus envisage an accuracy for τn of 10−4. The design of the experiment will be presented and possible sources of systematical errors will be discussed.
Supported by Maier-Leibnitz-Laboratorium and BMBF.