The PanEDM Experiment at ILL

Our group is part of an international collaboration called PanEDM, based at the Institute Laue-Langevin (ILL) in Grenoble, France.

The goal of PanEDM is to search for an electric dipole moment of the neutron (nEDM) with a sensitivity better than 10^-27 ecm, corresponding to an energy resolution of 10^-42 Joule, making it one of the most precise measurements ever performed. 

A nEDM would be a manifestation of new physics beyond the standard model of particle physics, as it would be time reversal symmetry violating. With the lack of signals for new physics at the LHC, the complementary approach using precision measurements like EDM searches becomes increasingly important.

Our experiment deploys Ramsey’s method of separated oscillatory fields, applied to UCN stored at room temperature in tow chambers. A change of the Larmor precession due to an electric field applied across the UCN storage chambers would be a sign of an EDM. Using one of the worldwide strongest sources of UCN, the new SuperSUN source of UCN, together with the world’s strongest magnetic shield, we hope to obtain a leading result over the next years.

The experiment is described in this publication:

D. Wurm et al., EPJ Web of Conferences 219

, 02006 (2019). (freely accessible preprint:

Further reading on the importance of EDM meaurements and a recent review of the field:

T. Chupp, P. Fierlinger, M. Ramsey-Musolf, J. Singh, Review of Modern Physics 91, 015001 (2019).(freely accessible preprint: