New search for the neutron electric dipole moment with ultracold neutrons at ILL

Abstract

The search for an electric dipole moment (EDM) of the neutron is a crucial test for theoretical particle physics models with violation of time and spatial invariance. A new experiment recently has been carried out at the High-Flux Reactor at Institut Laue-Langevin, using the upgraded double-chamber magnetic resonance spectrometer developed at Petersburg Nuclear Physics Institute. The result is interpreted as an upper limit on the value of the neutron EDM, $|{d}_{n}|<5.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}26}{e}_{}\phantom{\rule{4pt}{0ex}}\mathrm{cm}$ (90% C.L.). This article provides a detailed description of the setup and experimental procedures, along with a discussion of possibilities for further improvement of the experimental accuracy.