Search for the electric dipole of the neutron

by Guillaume Pignol (LPSC)


How was generated the matter/antimatter asymmetry in the Universe?
New physics, beyond the Standard Model, was certainly at play in an hypothetical phase of the early Universe called baryogenesis.
Since this new physics must induce a violation of CP symmetry,
it could be revealed in the laboratory by measuring a nonzero electric dipole moment of a spin 1/2 particle such as the neutron.

A collaboration of 16 institutions is searching for the neutron electric dipole moment (nEDM)
using the ultracold neutron source at the Paul Scherrer Institute (PSI) in Switzerland.
The most precise measurement of the nEDM has been produced by the Sussex/RAL/ILL spectrometer at the ILL research reactor in Grenoble,
it is compatible with zero, with the upper limit dn< 3E-26 ecm @90% C.L. [J.M. Pendlebury et al. PRD 92, 092003 (2015)].
We have operated an upgraded version of this apparatus to take data at PSI in the period 2015-2017 and we are now building the next generation spectrometer, n2EDM.
In my talk I will present the current status of the project.