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The measurement of a tau-neutorino mass

牛中子质量的测量

基本信息

批准号：
05044047
负责人：
NIWA Kimio
金额：
$ 6.72万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05044047/
关键词：
Neutrino oscillation Neutrino mass Tau-neutrino Dark matter Emulsion Scintillating fiber

项目摘要

CHORUS is the international project using the neutrino beam from super proton synchrotrn (SPS) of CERN (Center of Europ organization for Research of Nuclus). The object of this project is to observe the mass of tau-neutrino by the method of the oscillation from mu-neutrino to tau-neutrino. The identification of tau-neutrino could be done by detecting the produced tau by observing the trace of tau from produced point to the decay point in the photographic nucler emulsion.The detecter have many parts, target spectrometer calorimeter and muon spectrometer. We are contributing on the target the most important target of this experiment. This target has the sandwich structure of emulsion sheets and fiber trackers.The neutrino exposure has been finished on Novenber in 1995. The emulsion analysis, the most difficult job in this project, has been done by using Automatic emulsion analysis system originally developed by physists of Nagoya university. The number of analyzed neutrino interaction in the emulsion is more than 7700 neutorino interactions by 4 month scanning. This number is about 15% of all CHORUS, but already this number is 2 times higher than the most sensitive similler experiment, named E531 done in 1978. This experiment is sensitive to 1 eV in tauneutrino mass and 1% in mixing tau-neutrino to mu-neutrino.To finish all of the analysis, it take more two years.

CHORUS是利用欧洲核子研究中心（CERN）超级质子同步加速器（SPS）的中微子束的国际项目。本课题的目的是用从mu-中微子到tau-中微子的振荡方法来观测tau-中微子的质量。通过观察照相核乳剂中tau从产生点到衰变点的轨迹来检测产生的tau，可以进行tau中微子的鉴定。探测器由靶谱仪、量热仪和介子谱仪组成。我们正在为这个实验最重要的目标做贡献。该靶具有乳液片和纤维跟踪器的夹层结构。中微子暴露于1995年11月完成。利用名古屋大学物理学家独创的自动乳化液分析系统，完成了本项目中最困难的乳化液分析工作。经过4个月的扫描，发现乳化液中存在7700多个中微子相互作用。这个数字约占所有CHORUS的15%，但这个数字已经比1978年完成的最灵敏的类似实验E531高出2倍。该实验对τ中微子质量为1ev和τ中微子与μ中微子混合质量为1%敏感。要完成所有的分析，还需要两年多的时间。