Ultra-cold neutrons (UCN), i.e. neutrons with energy low enough that they undergo total reflection from a given surface at any angle of incidence, can be stored in magnetic and material bottles for periods ranging up to the neutron p-decay lifetime ( N 103 s).Starting with a discussion of the theoretical and historical background we review the development of the field from the first experimental observations to the present time with emphasis on the most recent developments and the remaining unsolved problems. We discuss the production and transport of UCN as well as their applications, and show the direction that future developments are likely to take.

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The possible existence of a neutron electric dipole (EDM) was put forward as an experimental question in 1949, 60 years ago, and still remains an outstanding question in modern physics. A review of the technical innovations that allowed for improving the experimental limit by nearly eight orders of magnitude (approximately a decade per decade) will be presented, along with a discussion of the prospects for further improvement.

The search for particle electric dipole moments (EDM) is one of the best places to look for physics beyond the Standard Model of electroweak interaction because the size of time reversal violation predicted by the Standard Model is incompatible with present ideas concerning the creation of the Baryon-Antibaryon asymmetry. As the sensitivity of these EDM searches increases more subtle systematic effects become important. We develop a general analytical approach to describe a systematic effect recently observed in an electric dipole moment experiment using stored particles[2]. Our approach is based on the relationship between the systematic frequency shift and the velocity autocorrelation function of the resonating particles. Our results, when applied to wellknown limiting forms of the correlation function, are in good agreement with both the limiting cases studied in recent work that employed a numerical/heuristic analysis. Our general approach explains some of the surprising results observed in that work and displays the rich behavior of the shift for intermediate frequencies, which has not been studied previously. In an appendix we give a new derivation of Egelstaf's theorem which we used in our study of the Diffusion theory (low frequency) limit of the effect.