accelerators at national laboratories and universities, small tandem accelerators, and cyclotrons. Access to small facilities with specific capabilities for particular experiments is also an important priority for this subfield. This area enriches the field of nuclear physics by sharing frontiers with other fields of physics, overlapping and enhancing work in atomic physics, high-energy particle physics, and astrophysics.
Although nearly all new facilities for nuclear physics will be exploited for testing the Standard Model, some future facilities have obvious utility that make them a high priority for the field. The new generation of intense sources of cold and ultracold neutrons hold the potential of allowing the Standard Model's version of the weak interaction to be better tested in a simple hadronic system. Precision studies of neutron beta decay and better searches for a neutron electric-dipole moment require access to the most intense research reactors and spallation sources available. Access to more intense neutron sources that become available in the next decade has a high probability of leading to a major discovery in this area of research.
The venerable area of nuclear beta decay has a new life because of the advent of new techniques of atom manipulation, new methods of polarizing nuclei, sophisticated online isotope separators, and new radiation detection methods. Ion or atom traps offer new opportunities for reducing the systematic uncertainties that now limit this research, but these techniques make more stringent demands on the production of particular radioactive species. A high-intensity exotic-beam accelerator would also be the source of radioactive atoms required for this research, and an exotic-beam facility is a high priority for this area of research.
In the next five years the newest solar neutrino experiments should finally resolve the question of whether or not the neutrino and its interactions are the cause of the solar neutrino problem. The discovery of neutrino masses and mixing could lead to the next scientific revolution, leading to the first significant change in the Standard Model two-and-a-half decades after it was established. Currently there are two other experimental indications that neutrinos may have mass. The signal from atmospheric neutrinos should be elucidated in a series of planned, long-baseline experiments at accelerators. The second indication appeared in a medium-energy nuclear physics accelerator experiment. Nuclear physicists will continue to participate in the follow-up experiments that should resolve these issues in the coming years.