Neutrino oscillation experiments with emulsion spectrometers

点击翻译按钮获取中文摘要

The OPERA experiment has found 4 tau-neutrino candidate events. 3 out of the 4 events are in hadronic decay channels of the tau lepton, where a hadron interaction could be a source of background. We therefore studied hadron interactions in an OPERA-like emulsion/lead target. We have found that they are well reproduced by a Monte Carlo simulation (MC) and have validated MC estimation of the background due to hadron interactions in the sample of tau decay candidates. As a result, the neutrino oscillations have been established with a significance of 4.2 sigma. We made emulsion detectors with springs and performed a test beam experiment. Appropriate strength of springs was obtained together with knowledge of brick handling. New techniques on a photomask to correct deformations in emulsion and on automatic scanning with wide-angle acceptance were successfully developed. These techniques will be applied in future neutrino experiments with emulsion spectrometers.