Neutrino-oscillation search with cosmic-ray neutrinos

A sensitive search for neutrino oscillations involving e, , and may be provided by measurements of the ratio of the total interaction rates of upward- and downward-going cosmic-ray neutrinos within a massive (10 kton) detector. Assuming mixing between all pairs of e, , and , the experiment is capable of observing time-averaged probabilities Pet and Pt of magnitude set by mixing strengths corresponding to, e.g., the d- to s-quark mixing strength, and of reaching the limit mij2|mi2-mj2|10-4 eV2, where mi, and mj are neutrino mass eigenstates, and Pe and P are the probabilities for e and , respectively, to oscillate into after traversing a distance L diameter of the Earth. Possible ambiguities may be resolved through comparison of the ratios NeN for the upward- and downward-going neutrinos.