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Search for neutrino point sources in the southern sky hemisphere

在南天半球寻找中微子点源

基本信息

批准号：
13640288
负责人：
TAKITA Masato
金额：
$ 2.37万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640288/
关键词：
Super-Kamiokande upward-going muons atmospheric neutrinos southern sky hemisphere AGN point sources

项目摘要

We search for celetial neutrino point sources in the southern sky hemisphere by neutrino induced upward-going muon detected with the Super-Kamiokande detector. Search for neutirno signal from active galactic nuclei (AGN) is particularly interesting. The major background of atmosperic neutrino origin below 100 GeV is estimated to be 0.05 events/year. We have accumulated approximately 2000 neutirino induced upward-going muon events during 1600 detector live days from 1996 to 2001. We perform a Monte Carlo simulation as well as an analytic calculation of neutrino events, assuming AGN neutrino sources. Other analysis software are developed whenever needed. We spend our time extensively on the development of an automatic event reconstruction program of through-going and stopping muons in the Super-Kamiokande detector. The expected number of upward-going muons induced by atmospheric neutrinos is estimated to be roughly 2000 events which is reasonably consistent with the observed number. We plot the observed upward-going muon events in the celestial coordinates and study the event density distribution. We check whether there exists excess of upward-going events from acelecial point sources againt the atmospheric neutrino background events. However, we find no statistically significant excess in the southern sky hemisphere. Accordingly, we set the most stringent upper limit of 10^<-14>/cm^2/s at 90% confidence level on neutrino-induced upward-going muons from celetial point sources.

利用Super-Kamiokande探测器探测到的中微子感生上行μ介子，在南天半球寻找著名的中微子点源。寻找活动星系核（AGN）的neutirno信号特别有趣。100 GeV以下的大气中微子起源的主要本底估计为0.05个事件/年。从1996年到2001年，我们在1600个探测器寿命日内积累了大约2000个neutirino诱导的上行μ子事件。我们进行了Monte Carlo模拟以及中微子事件的解析计算，假设活动星系核中微子源。其他分析软件也在需要时开发。我们花了大量的时间在开发一个自动事件重建程序的通过和停止μ子在超级神冈探测器。大气中微子诱发的上行μ子的预期数量估计大约为2000个事件，这与观测到的数量相当一致。我们在天球坐标系中绘制了观测到的上行μ介子事件，并研究了事件密度分布。我们检验了大气中微子背景事件与非点源上行事件之间是否存在过剩。然而，我们在南半球的天空中没有发现统计上显著的过量。因此，我们<-14>在90%的置信水平下，将中微子诱导的来自Celite点源的上行μ子的最严格上限设定为10^ /cm ^2/s。