Progress in neutrino oscillation physics

对T2K实验中的前置探测器系统进行了详细的研究。T2K是新一代中微子振荡实验。中微子由J-PARC加速器产生，并在Super-Kamiokande中被探测到。这项实验将于2009年开始。这个实验的主要目标之一是寻找非零中微子混合角之一的非零中微子θ_&lt；13&gt；，目前尚不清楚。前置探测器应该能够在没有振荡的情况下预测中微子的能谱和中微子味道。详细的蒙特卡罗研究得出结论，一个水切伦科夫探测器，直径约5000个20厘米的光电倍增管，位于中微子产生目标约1.8公里处，应该有足够高的性能来进行这次实验。此外，还研究了T2K中微子束的未来可能性。结论是位于神冈和韩国的大型水切伦科夫探测器对中微子CP相和质量等级的测量应该具有很高的灵敏度。根据在超级神冈和K2K中微子束事件中观测到的大气中微子事件，研究了中微子振荡。在中微子质量和混合角方面得到了各种新的结果。所有已有的结果都是在标准中微子振荡框架内解释的。

A detailed study on the front detector system at the T2K experiment was carried out. T2K is a next generation neutrino oscillation experiment. Neutrinos are generated by the J-PARC accelerator and are detected in Super-Kamiokande. The experiment will start in 2009. One of the main goals of this experiment is the search for non-zero θ_<13>, which is one of the neutrino mixing angles and is not known yet. The front detector should be able to predict the neutrino energy spectrum and neutrino flavor without oscillation. Detailed Monte Carlo study concluded that a water Cherenkov detector with about 5000 20cm-diameter photomultipliers, located about 1.8km from the neutrino production target should have a sufficiently high performance for this experiment.In addition, future possibilities with the T2K neutrino beam were studied. It was concluded that large water Cherenkov detectors located in Kamioka and in Korea should have a very high sensitivity to the measurement of the neutrino CP phase and mass hierarchy.Studies of neutrino oscillations based on atmospheric neutrino events observed in Super-Kamiokande and K2K neutrino beam events were carried out. Various new results on neutrino masses and mixing angles were obtained. All the existing results are explained within the standard neutrino oscillation frame work.