Lay summary

Measurements of the neutron Electric Dipole Moment (nEDM) with sensitivities better than 10^-26 e.cm are considered to be of top priority by the particle physics community, since they may provide information on new sources of CP violation and thus give clues as to the presence of physics ‘Beyond the Standard Model’ (BSM). An improved nEDM measurement is timely and will complement results expected from other projects sensitive to BSM physics, e.g. concerning supersymmetry signatures, such as experiments at the Large Hadron Collider (CERN) or searches for forbidden lepton-flavour changing processes such as the MEG experiment at the Paul Scherrer Institut (PSI). A nEDM project is pursued by an international collaboration at PSI (nedm.web.psi.ch) in a staged approach using an existing apparatus and developing a next measurement system.


A prerequisite for a successful nEDM experiment is the control of magnetic fields at the location of the experiment down to a level of a few 10 fT. To fight against external magnetic field distortions and fluctuations, the experiment uses a passive multilayer mu-metal shielding in combination with a surrounding active field compensation system. This project here aims at the development of a superior active compensation system relying on an arrangement of multiple coils and multiple magnetic field sensors with an advanced feedback system based on fast real time field calculations.