Study of neutrino oscillation using low-energy solar neutrinos

如果要确定太阳中性生长，我们必须精确测量8B太阳中性以下6.5 MeV以下的能量谱。在那些能源区有一个巨大的背景。这个项目的目的是对那些软件的背景特征和开发的软件的特性进行调查。对于无线电同位素背景，我们可以测量D1222 D1 Rn由使用高敏感性无线电探测器，并获得为1.4mBq/m D13 D1用于输入纯净水。在其他方面，我们在数据中看到了一个背景集群，围绕着超级卡米坎德探测器。Those background had same life time asイイD1222イエD1Rn， however， the measured concentration was 4 mBq/mイD13イエD1。这并不总是与一个雷达探测器观察到的一致。Using Monte Carlo simulation ofイイD1214イエD1Bi， which is daughter nuci ofイイD1222イエD1Rn， andイD1208イエD1Tl for thorium series， I found about 50%contamination ofイD1208イエD1Tl in the background。即使是我们 ... More 提取无线电同位素的背景完全完整，大约90%的背景仍然保留。那些偶然重叠的事件的大多数背景因素，因为他们有一个独特的特征，他们对垂直重建的不良表现，并且在垂直位置周围的价值几乎相同。使用此字符。我开发了软件来排除这些数据中的事件。适用于1997年5月的真实数据，大约90%的背景没有无线电同位素可以被排除。太阳中性信号保持90%的有效性，而系统性错误应该少2%。现在，我们正在处理1999年10月之前的整个数据集，初步结果显示，5.5-6.0 MeV和6.0- 6.5 MeV标准太阳能模型的预期通量为0.48和0.43次，对此，请注意。从这一结果中，似乎有一个平坦的光谱，然后也存在着排除小角度解决方案的可能性。在课程中，我们仍然需要更多的数据统计数据，如何，这个项目可以显示允许所有4个太阳能实验的中性生长参数的约束能力。Less（低）

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