Basic Research for a Large Liquid Scintillator Detector

本研究的目的是为了研究中微子振荡而建造的大型液体闪烁体探测器，测量液体闪烁体的基本性质。为了建造这样的探测器，我们需要大量非常昂贵的液体闪烁。降低探测器成本的一种方法是用溶剂如矿物油稀释闪烁体。然而，没有关于这种混合液体闪烁体的性质的信息。为此，我们制作了一个2.5cm × 7 cm φ的测试探测器，用两个光电管测量液体闪烁体的吸收长度。实验中使用的是NE 224和0.976MeV的Bi转换电子<207>，实验探测器采用了屏蔽环的设计，避免了管壁的光反射。在检查光电管的稳定性之后，我们获得了NE 224 μ =5.8（]SY ±-. [）0.9m。由于NE 224的吸收长度没有信息，我们重复测量，发现测量值彼此一致。对于将矿物油混合到液体闪烁体中，我们需要研究和建立混合方法，然后测量混合物的吸收长度。最后，感谢文部科学省通过该补助金建立了液体闪烁体吸收长度的测定方法。

This study aims to measure the basic properties of liquid scintillator for a large liquid scintillator detector, which Tohoku university group is planning to build for studying the neutrino oscillation. To build such a detector, we need a large amount of the very expensive liquid scintillation. Oneway to reduce the cost of the detector is to dilute the scintillator with solvent such as mineral oil. However, no information for the properties of such a mixed liquid scintillator. Thus, we made a test detector of 2.5cm*7cm phi to measure the absorption length of the liquid scintillator with two phototubes. We use NE224 and 0.976MeV conversion electrons from ^<207>Bi for this test.The test detector was designed to avoid the light reflection from the tube wall by putting shielding rings. After examining the stability of the phototubes, we obtained the absorption length (mu) of NE224mu=5.8(]SY.+-。[)0.9m.Since no information is available for the absorption length of NE224, we repeated the measurements and found that the measured values are consistent with each other.For mixing mineral oil to liquid scintillator, we need to study and establish the mixing method before measuring the absorption length of mixture. Finally, we thank the Ministry of Education, Science, Sports and Culture that we could establish the method of measuring absorption length of liquid scintillator through this Grant-in-Aid.