Precise measurement of the zenith-angle distribution of atomospheric neurtrinos and a study of neutrino oscillations

我们研究了利用超级Kamiokande的大气层中性数据的中性分布，并展示了类似于多GeV muon的数据的显著缺陷。Up/down ratio of these events was 0.56 ± 0.04（statistical） ± 0.01（systematic） and deviated from the expectation （unity） in the absence of neutrino oscillations by more than 8 standard deviations。数据可以自然地被中性生长所揭示，自从中性生长在长距离旅行后，中性生长所改变了他们的口味。本说明书是由中微子事件的muon/电子比率支持的，并由上行的muon事件的详细研究。我们将大气中性数据从超Kamiokandegive evidence for neutrino oscillations.大气中性数据由muon-neutrinos和tau-neutrinos之间的中性数据解释。好吧，这是有可能用在单神经神经和非交互性类固醇神经之间引入神经生长的数据。我们仔细研究了这一可能性，并发现了类固醇中性的生长在99%的C.L.摘要中，我们将神经性的生长在muon-neutrinos和tau-neutrinos之间。中性质质量平方之间的差异介于2 - 5 × 10之间，D13-D1 eV介于D12-D1之间，而两个中性质之间的混合角度介于22 θ > 0.88，在90% C.L.。

We studied neutrino oscillations using the atmospheric neutrino data from Super Kamiokande.Multi-GeV muon-like data showed a significant deficit of the upward-going events. Up/down ratio of these events was 0.56 ± 0.04(statistical) ± 0.01(systematic) and deviated from the expectation (unity) in the absence of neutrino oscillations by more than 8 standard deviations. The data can be naturally explained by neutrino oscillations, since the neutrinos change their flavor by neutrino oscillations after traveling long distances. This conclusion was supported by the muon/electron ratio of the neutrino events and by detailed studies of the upward-going muon events. We conclude that the atmospheric neutrino data from Super-Kamiokande give evidence for neutrino oscillations.The atmospheric neutrino data are explained by the neutrino oscillations between muon-neutrinos and tau-neutrinos. However, it is possible to explain the data by introducing neutrino oscillations between muon-neutrinos and non-interacting sterile-neutrinos. We have carefully studied this possibility and found that the oscillations to sterile neutrinos are disfavored at about 99% C.L.In summary, we conclude that neutrino oscillations are between muon-neutrinos and tau-neutrinos. The difference of the neutrino mass squared is between 2 〜 5 × 10ィイD13ィエD1eVィイD12ィエD1, and the mixing angle between the two neutrinos is sin22 θ > 0.88, at 90% C.L.