Colloquium Seminar: The quest for an electric dipole moment of the neutron
Speaker: Philipp Schmidt-Wellenburg, Paul Scherrer Institute
Location: Auditorium
Time: 14:00
The search for a neutron electric dipole moment (nEDM) is generally considered as an excellent experiment to search for physics beyond the Standard Model of particle physics. A discovery of an nEDM value larger than the SM prediction (dn≤1E-31 ecm) might help to explain the baryon asymmetry of the Universe, and shed light on to the strong CP problem. The talk will briefly review motivation and the classical technique for searching for an nEDM. This includes the production of ultracold neutrons (UCN), which will be discussed using the example of a small prototype UCN source based on superfluid helium. In particular results will be presented from an investigation of UCN production in superfluid helium under pressure [PSW et al., PRC 92, 024004 (2015)]. Then the status and technical details of the experiment at the Paul Scherrer Institute (PSI) in Switzerland will be presented, where a collaboration of 14 institutions is searching for the nEDM using UCN. We intend to improve the current upper limit by the RAL/Sussex/ILL collaboration, dn< 2.9E-26 ecm @90% C.L. [C.Baker et al., PRL 97, 131801 (2006)], by using the same but improved and upgraded instrument connected to the new solid deuterium based UCN source. A new developed spin-echo technique using UCN gives us a handle on magnetic field gradients and the UCN energy spectrum [S.Afach et al., PRL 115, 162502 (2015)].