Realtime Measurement of pp and ^7Be Solar Neutrinos

实时测量 pp 和 ^7Be 太阳中微子

• 批准号: 12640247
• 负责人: INOUE Kunio
• 金额: $ 2.3万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640247/
• 关键词: Solar Neutrino; Gadolinium; Liquid Scintillator; 液体シンチレータ

Research and development for a realtime measurement of low energy solar neutrinos with charged current interaction has been performed. The ^<160>Gd atom is quite suitable for this purpose because of its very low energy reaction threshold enabling pp neutrino detection and of very characteristic three fold coincidence signal useful for background rejection. In this research, it was focused on solving Gadolinium into fast liquid scintillator so that indispensable three fold coincidence can be achieved. Performance measurement of the Gadolinium loaded liquid scintillator and feasibility test as low energy solar neutrino detector are also carried out. Performing wide survey of solvents and Gadolinium compounds, an excellent combination of PsuedoCumene (60 %), detergent NS210 (40 %) and Gd(NO_3)_36H_2O was found that it can hold Gadolinium up to 8 weight %. The performance of the Gadolinium loaded liquid scintillator at 5wt % was measured to be ; 2ns as decay time, 3500photons/MeV, effective light transmission 39 cm, alpha quench 7.4 at 7.8MeV and alpha dicrimination 95 % resulting applicable to the low energy solar neutrino observation. A simulation of 1m^3 size detector provided efficiencies of three fold coincidence identification to be 65 % for ^7Beneutrino signal and 63 % for pp neutrino even with a selection criteria that has less than 0.05 % misidentification probability to the problematic ^<152>Gd alpha decay. This scintillator costs only one tenth in relative to the other competing developments. Thus, the very competitive Gadolinium loaded liquid scintillator has been successfully developed.

已经进行了带电电流相互作用的低能太阳中微子实时测量的研究和开发。 ^ 160 Gd原子非常适合此目的，因为其非常低的能量反应阈值能够实现pp中微子检测，并且具有非常特有的三倍重合信号，可用于背景抑制。本研究的重点是将钆溶解到快速液体闪烁体中，以实现不可或缺的三倍重合。还进行了载钆液体闪烁体的性能测量和作为低能太阳中微子探测器的可行性试验。对溶剂和钆化合物进行了广泛的调查，发现PsuedoCumene (60%)、清洁剂NS210 (40%) 和Gd(NO_3)_36H_2O 的完美组合可以容纳高达8%（重量）的钆。 5wt% 钆负载液体闪烁体的性能经测量为：衰减时间2ns，3500光子/MeV，有效透光率39cm，7.8MeV下α淬灭7.4，α分辨95%，适用于低能太阳中微子观测。 1m^3 尺寸探测器的模拟提供了 ^7Beneutrino 信号的三倍重合识别效率为 65%，pp 中微子的三倍重合识别效率为 63%，即使选择标准对有问题的 ^<152>Gd 的错误识别概率小于 0.05%阿尔法衰变。与其他竞争性开发产品相比，这种闪烁体的成本仅为十分之一。由此，极具竞争力的载钆液体闪烁体已经研制成功。