Köln 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HK: Physik der Hadronen und Kerne
HK 45: Instrumentation and Applications VI
HK 45.4: Vortrag
Donnerstag, 11. März 2004, 17:30–17:45, C
A superconducting magnetic UCN trap for precise neutron lifetime measurements — •Rüdiger Picker, Igor Altarev, Johannes Bröcker, Andreas Frei, Andreas Gschrey, Erwin Gutsmiedl, F. Joachim Hartmann, Stephan Paul, Gerd Petzoldt, Wolfgang Schott, Daniele Tortorella, and Oliver Zimmer — Physik-Department E18, Technische Universität München
The measurement of the neutron lifetime τn opens the way to determine the coupling constants of weak interaction and hence the element Vud of the CKM matrix precisely. Latest experimental results indicate this matrix to deviate 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 whose nature is not yet fully understood. Therefore systematical errors cannot be decreased much below their present values. Magnetic storage has recently been proven to be a viable alternative. In our planned experimental setup the volume between two nested cylinders made from magnetic multipole fields is used to store UCN. The field is produced by superconducting coils with the gravitational field playing the role of the upper lid of the bottle. τn shall be measured by real-time detection of decay protons as well as by counting the integral number of neutrons after a predetermined storage time. Using a new high-density UCN source we expect to store 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.