用ICARUS探测器在CNGS中微子束中探测LSND异常
Experimental search for the LSND anomaly with the ICARUS detector in the CNGS neutrino beam
摘要：
我们报告的早期结果从ICARUS实验上寻找nu_mu到nu_e信号由于LSND异常。搜索是用位于格兰萨索实验室的ICARUS T600探测器进行的，该探测器从欧洲核子研究中心接收平均能量约为20 GeV的CNGS中微子，飞行路径约为730公里。LSND异常将表现为nu_e事件的过剩，其特征是快速能量振荡，平均值约为sin ^2（1.27 Dm ^2_new L/ E_nu）= 1/2。目前的分析基于1091个中微子事件，约占ICARUS在2010-2011年收集的数据的50%。发现了两个明显的nu_e事件，而常规源的预期值为3.7 ± 0.6。在我们的观测范围内，这一结果与不存在LSND异常是一致的。在90%和99%的置信水平下，分别设定3.4和7.3个事件的极限，对应于5.4 × 10^-3和1.1 × 10^-2的振荡概率。该结果将LSND异常的开放选项窗口严格限制在（Dm ^2，sin^2（2 θ））_new =（0.5 eV^2，0.005）附近的狭窄区域内，在该区域内，当前ICARUS限值、KARMEN公布的限值以及LSND和MiniBooNE合作组织公布的阳性信号之间存在总体一致性（90% CL）。
英文摘要：
We report an early result from the ICARUS experiment on the search for nu_mu to nu_e signal due to the LSND anomaly. The search was performed with the ICARUS T600 detector located at the Gran Sasso Laboratory, receiving CNGS neutrinos from CERN at an average energy of about 20 GeV, after a flight path of about 730 km. The LSND anomaly would manifest as an excess of nu_e events, characterized by a fast energy oscillation averaging approximately to sin^2(1.27 Dm^2_new L/ E_nu) = 1/2. The present analysis is based on 1091 neutrino events, which are about 50% of the ICARUS data collected in 2010-2011. Two clear nu_e events have been found, compared with the expectation of 3.7 +/- 0.6 events from conventional sources. Within the range of our observations, this result is compatible with the absence of a LSND anomaly. At 90% and 99% confidence levels the limits of 3.4 and 7.3 events corresponding to oscillation probabilities of 5.4 10^-3 and 1.1 10^-2 are set respectively. The result strongly limits the window of open options for the LSND anomaly to a narrow region around (Dm^2, sin^2(2 theta))_new = (0.5 eV^2, 0.005), where there is an overall agreement (90% CL) between the present ICARUS limit, the published limits of KARMEN and the published positive signals of LSND and MiniBooNE Collaborations.
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