Neutrino factories: Realization and physics potential

Neutrino Factories offer an exciting option for the long-term neutrino physics program. This new type of neutrino facility will provide beams with unique properties. Low systematic uncertainties at a Neutrino Factory, together with a unique and precisely known neutrino flavor content, will enable neutrino oscillation measurements to be made with unprecedented sensitivity and precision. Over recent years, the resulting neutrino factory physics potential has been discussed extensively in the literature. In addition, over the last six years the R&D necessary to realize a Neutrino Factory has been progressing, and has developed into a significant international activity. It is expected that, within about five more years, the initial phase of this R&D program will be complete and, if the community chooses to build this new type of neutrino source within the following decade, neutrino factory technology will be ready for the final R&D phase prior to construction. In this paper (i) an overview is given of the technical ingredients needed for a Neutrino Factory, (ii) beam properties are described, (iii) the resulting neutrino oscillation physics potential is summarized, (iv) a more detailed description is given for one representative Neutrino Factory design, and (v) the ongoing R&D program is summarized, and future plans briefly described.