  The existence of electric dipole moments (EDM) for fundamental particles
signals time-reversal symmetry (T) violation accompanied by violation of parity
(P); only upper limits have been established to date. Time-reversal violation
in turn implies CP violation under the assumption that CPT is a good symmetry.
The neutron is an attractive system for an EDM search, both because it is neu-
tral and because a neutron EDM would be relatively easier to interpret than the
comparable quantity for a nucleus or even an atom. We introduce briefly the key
experimental requirements for such search and describe some aspects of the
neutron EDM experiment planned for the Spallation Neutron Source at the U.S.
Oak Ridge National Laboratory.
