arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0901.1645hep-ex
收藏

在带有质子识别的大型水切伦科夫探测器中大气中微子事件的运动学重建

Kinematic reconstruction of atmospheric neutrino events in a large water Cherenkov detector with proton identification

Kamiokande Collaboration

摘要:

我们报告的超级神冈探测器的质子识别方法的发展。这个新的工具被应用到搜索事件与一个单一的质子轨道,一个高纯度的中性电流样品的兴趣无菌中微子搜索。在使用神经网络进行选择后,我们在SK-1和SK-II组合数据中观察到38个事件,对应于2285.1天的暴露,估计信号与背景比为1.6比1。质子识别也适用于直接搜索的荷电准弹性(CCQE)事件,获得高精度的样品完全运动学重建的大气中微子,这是以前没有报道的水切伦科夫探测器。该样本的CCQE分数为55%,其中微子(与反中微子相反)分数为91.7+/-3%。我们在SK-1和SK-II数据集中选择了78个mu样事件和47个e样事件。有了这些数据,一个明确的天顶角扭曲的中微子方向本身的亚GeV的μ子中微子的样品中的轻子角相关入射中微子是弱的。我们使用CCQE样品的中微子L/E分布单独拟合nu_mu->nu_tau振荡,产生了与我们以前的结果相容的宽接受区域,并且排除了3 σ处的无振荡假设。

英文摘要:

We report the development of a proton identification method for the Super-Kamiokande detector. This new tool is applied to the search for events with a single proton track, a high purity neutral current sample of interest for sterile neutrino searches. After selection using a neural network, we observe 38 events in the combined SK-I and SK-II data corresponding to 2285.1 days of exposure, with an estimated signal to background ratio of 1.6 to 1. Proton identification was also applied to a direct search for charged-current quasi-elastic (CCQE) events, obtaining a high precision sample of fully kinematically reconstructed atmospheric neutrinos, which has not been previously reported in water Cherenkov detectors. The CCQE fraction of this sample is 55%, and its neutrino (as opposed to anti-neutrino) fraction is 91.7+/-3%. We selected 78 mu-like and 47 e-like events in the SK-I and SK-II data set. With this data, a clear zenith angle distortion of the neutrino direction itself is reported in a sub-GeV sample of muon neutrinos where the lepton angular correlation to the incoming neutrino is weak. Our fit to nu_mu->nu_tau oscillations using the neutrino L/E distribution of the CCQE sample alone yields a wide acceptance region compatible with our previous results and excludes the no-oscillation hypothesis at 3 sigma.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑