[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Tue 2009-06-23 at 14:00

Location:  Auditorium          

Speaker:   Rüdiger Picker (TU Munich)

Title:     PENeLOPE, on the way towards a new precise neutron lifetime measurement

Abstract: The neutron lifetime allows access to fundamental parameters of the weak interaction.  Therefore, measurements of the lifetime provide direct tests of the standard model of particle physics.  Moreover, a precise knowledge of the neutron lifetime is important for astrophysical models. However, a recent result disagrees with the PDG average of 885.7 +-0.8 s by roughly 6 standard deviations.

To resolve this discrepancy,  we are developping an experiment with a superconducting magnetic trap for ultracold neutrons (UCN) at Technische Universität München, Physik Department E18. These UCN will be trapped in a multipole field of a flux density up to 2 T and will be bound by the gravitational potential to the top. This makes the extraction and detection of the decay protons possible and allows a direct measurement of the neutron decay rate.  Our envisaged precision of < 0.1 s demands almost lossless storage and good knowledge of systematic errors, which could result from neutron spin flip and high energetic UCN which leave the storage volume only slowly. Therefore, the neutron spectrum is cleaned by an absorber.  The big storage volume of 800 liters and the expected high neutron flux of the UCN source at the FRMII give more than 107 neutrons per filling of the storage volume.  This will allow us to concentrate on systematic effects, as the necessary statistics is reached within days; a crucial point for this kind of experiments.  The talk will motivate the measurement, describe it in detail, present simulations and discuss systematic effects and investigations.

Stimulants available 15 minutes before the talk.

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