The neutron electric dipole moment.

Measurements of permanent electric dipole moments (EDM) of particles, atoms or molecules present one of the most promising routes to find new physics beyond the Standard Model (SM) and shed more light on the as yet unexplained asymmetry between the amounts of matter and antimatter in the universe. The observed small size of the neutron EDM has already eliminated many theories, and is pressing on other extensions to the SM, including supersymmetric ones of which most predict neutron EDM values in the range from 10^-26 to 10^-28 e.cm. With the currently best limit for the neutron EDM of |d_n| > 2.9 x 10-26 e.cm (90% CL) and the SM prediction of d_n = 10-32 e.cm, which is far too small to explain the observed matter-antimatter asymmetry, a large range of values still remains to be discovered. Neutron EDM experiments have thus become important particle physics experiments. Indeed, besides their discovery potential, any improvement in sensitivity, also of a null result, will have strong impact on different extensions to the SM. With this project we intend to improve the sensitivity to the neutron EDM in a first step to about 2.5 x 10^-27 e.cm, using ultracold neutrons from the new performant source at the Paul Scherer Institute with the EDM apparatus that was constructed and optimized during the past years. In a second phase a further improvement in sensitivity to about 2.5 x 10^-28 e.cm is aimed at with a new and more performant setup that is being developed in parallel.