NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS AND POLARIZED HE-3

A brief review of the history of the experimental search for the neutron electric-dipole moment (EDM) is presented, followed by a discussion of the ''state of the art'' experimental techniques based on the storage of ultracold neutrons. Also discussed is the recent work on the construction of an improved experiment incorporating a Hg-199 magnetometer within the ultracold neutron storage volume. We then review a number of well-known experimental and theoretical results and propose an entirely new experimental technique to search for the neutron EDM based on storing together, in superfluid He-4, polarized ultracold neutrons and a polarized gas of He-3 atoms; this forms a unique system of two spins interacting by means of a spin-dependent mutual absorption. Such a system appears to be ideally suited for use in a neutron EDM search. Following a brief description of the method, we present an analysis of the dynamics of such a system and calculate the statistical uncertainties to be expected in an EDM search We how that, in principle, improvement by a factor of over 1000 in the experimental limit is possible. This limit would be more than sufficient to determine whether the known CP violation leads to the observed cosmological baryon asymmetry and, in addition, would set very strict limits on the supersymmetric, multi-Higgs, and left-right-symmetric models of CP violation. We conclude with a discussion of come technical questions related to the proposed experimental technique.