The search for the neutron electric dipole moment
Prof. Klaus Kirch (Paul Scherrer Institut, Villingen, Schweiz)

Nonzero permanent electric dipole moments (EDM) of fundamental systems like particles, nuclei, atoms or molecules violate parity and time reversal invariance. Invoking the CPT theorem, time reversal violation implies CP violation. Although CP-violation is implemented in the standard electro-weak theory, EDM generated this way remain undetectably small. However, this CP-violation also appears to fail explaining the observed baryon asymmetry of our universe.
Extensions of the standard theory usually include new CP violating phases which often lead to the prediciton of larger EDM.
EDM searches in different systems are complementary and various efforts worldwide are underway, but no finite value could be established yet.
The prototype of an EDM search is the one for the EDM of the neutron.
It has the longest history and at the same time is at the forefront of present research. With an international collaboration we are preparing for a new measurement of the neutron EDM at PSI. I will report on the commissioning of the high intensity source of ultracold neutrons at PSI, the setup of the neutron EDM apparatus and our approach to improving its sensitivity.