Neutron Lifetime Measurement with the UCN trap-in-trap MAMBO II

by Prof. Klaus Schreckenbach (Physik Department E21, TU München)

Thursday 10 Jun 2010, 09:15 → 10:15 Europe/Berlin

E18 seminar room

Abstract We have measured the free neutron lifetime by storage of ultra-cold neutrons (UCN) in a Fomblin coated UCN trap of in-situ variable size. The method was initially developed by W. Mampe et al. with MAMBO I and improved by the addition of a prestorage volume yielding a well defined UCN spectrum for storage in the main trap. By extrapolation to infinite trap size using the time scaling method we obtain for the free neutron lifetime 880.7 ± 1.3 ± 1.2 s. Data from different UCN spectra and trap temperature gave consistent results. Combining our result with other experimental values we derived an average value of 881.8(1.5) s and use it for the evaluation of the CKM matrix element Vud.