Study of neutrino oscillation using low-energy solar neutrinos

利用低能太阳中微子研究中微子振荡

• 批准号: 10640251
• 负责人: FUKUDA Yoshiyuki
• 金额: $ 2.5万
• 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: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640251/
• 关键词: neutrinos; solar neutrinos; neutrino oscillation; neutrino mass; Super-Kamiokande

In order to establish the solar neutrino oscillation, we must measure the energy spectrum of 8B solar neutrinos below 6.5 MeV precisely. However there are a huge background in those energy region. The purpose of this project is that the investigate the characteristics of those background and development of software which excludes them. For radio-isotope backgrounds, we could measure ィイD1222ィエD1Rn by using high sensitive radon detector, and obtained as 1.4mBq/mィイD13ィエD1 for input purified water. On the other hands, we have seen background clustered around the bottom of Super-Kamiokande detector in the data. Those background had same life time as ィイD1222ィエD1Rn, however, the measured concentration was 4mBq/mィイD13ィエD1. It was not consistent with one observed by the radon detector. Using Monte Carlo simulation of ィイD1214ィエD1Bi, which is daughter nuclei of ィイD1222ィエD1Rn, and ィイD1208ィエD1Tl for thorium series, I found about 50% contamination of ィイD1208ィエD1Tl in the background. Even though we e … More xtract the radio-isotope Background completely, almost 90% of background still remains. Most of those background consists of an accidental overlapped events, because they had a unique characteristics of their low goodness for the vertex reconstruction and almost same values around their vertex position. Using this character. I developed the software to exclude those event from data. Applying for real data from May 1997, about 90% of background without radio-isotope could be excluded. The efficiency of solar neutrino signal keeps 90%, and the systematic error should be less 2%. Now we are processing for whole data-set until October 1999, and the preliminary results were obtained by 0.48 and 0.43 times the expected flux from standard solar model for 5.5-6.0 MeV and 6.0-6.5MeV, respectively. From this results, there seems to be flat spectrum then there also exist the probability to exclude the small angle solution. Of course, still we need more statistics of data, however, this project could show the ability of constraint for allowed neutrino oscillation parameters by all 4 solar neutrino experiments. Less

为了建立太阳神经元振荡，我们必须精确地测量8B太阳神经元的能量光谱。但是，这些能源区域有很大的背景。该项目的目的是调查那些背景的特征和不包括它们的软件的特征。对于放射异位背景，我们可以使用高灵敏的ra探测器测量D1222E D1RN，并获得为1.4MBQ/MER MER D13E D1用于输入纯净的水。另一方面，我们已经看到数据中的Super-Kamiokande检测器的底部聚集在数据中。这些背景的寿命与D1222E D1RN相同，但是测得的浓度为4MBQ/MER D13E D1。使用D1214E D1BI的Monte Carlo模拟，该模拟是D1222，D1RN和D1208的女儿核，D1208，D1TL，D1TL用于Thorium Series，我发现背景中D1208，D1TL的污染约为50％。即使我们……更多地完全Xtract射电 - 同位素背景，仍然存在几乎90％的背景。这些背景大多数都包括一个意外的重叠事件，因为它们具有其对顶点重建的低度的独特特征，并且在其顶点位置周围具有几乎相同的值。使用此字符。我开发了该软件，将这些事件排除在数据之外。从1997年5月开始申请实际数据，可以排除大约90％的没有放射异位的背景的背景。太阳神经元信号的效率保持90％，系统误差应降低2％。现在，我们一直在处理整个数据集，直到1999年10月，初步结果是从标准太阳能模型（5.5-6.0 MEV和6.0-6.5mev）的0.48和0.43倍的预期通量获得的。从此结果，似乎存在扁平光谱，然后也存在排除小角度解的概率。当然，我们仍然需要更多的数据统计数据，但是，该项目可以通过所有4种太阳神经元实验来显示允许神经元振荡参数的约束能力。较少的

项目成果

Y. Fukuda et al.: "Calibration of Super-Kamiokande using an electron LINAC"Nuclear Instruments and Methods in Physics Research. A・421. 113-129 (1999)

Y. Fukuda 等人：“使用电子直线加速器校准超级神冈”核物理研究仪器和方法 A·421（1999 年）。

Y. Fukuda, et al.: "Calibration of Super-Kamiokande using an electron LINAC"Nuclear Instruments and Method in Physics Research. A421. 113-129 (1999)

Y. Fukuda 等人：“使用电子直线加速器校准超级神冈”物理研究中的核仪器和方法。

Y. Fukuda et al.: "Calibration of Super-Kamiokande using an electron LINAC"Nuclear Instrument and Method in Physics Research. A421. 113-129 (1999)

Y. Fukuda 等人：“使用电子直线加速器校准超级神冈”物理研究中的核仪器和方法。

Y.Fukuda et al.: "Measurements of the Solar Neutrinos Flux from Super-Kamiokande's First 300 days." Physical Review Letters. 81. 1158-1162 (1998)

Y.Fukuda 等人：“超级神冈探测器前 300 天太阳中微子通量的测量”。

Y. Fukuda, et al.: "Constraints on neutrino oscillation parameters from the measurement of day-night solar neutrino fluxes at Super-Kamiokande"Physical Review Letters. 82. 1810-1818 (1999)

Y. Fukuda 等人：“超级神冈探测器昼夜太阳中微子通量测量对中微子振荡参数的限制”物理评论快报。