Some Neutrino Oscillation Experiments in the United States

During the seventy years since Pauli postulated the existence of the neutrino to understand nuclear β decay, there has been steady progress in discovering the properties of this most elusive of the known elementary particles. The most recent contribution to our understanding of them has been the growing body of evidence pointing toward at least three types of neutrinos whose flavor eigenstates differ from their mass eigenstates, leading generally to flavor oscillations as a neutrino beam propagates ([1]-[4]). This picture provides an explanation of the observations but it cannot yet be considered as fully established; there are alternative theoretical models ([8]) consistent with the current experimental observations but with different predictions for some future ones. Nevertheless, neutrino oscillation is the best motivated and most popular working model at present: past experiments have been interpreted using it and future experiments, to be discussed here, are designed based on it. A major physics goal is either to unequivocally confirm the oscillation model and precisely determine its parameters or to clearly show that some other physics is producing the phenomena seen so far.