大亚湾反应堆中微子振荡实验通过在不同基线位置测量核电反应堆产生的反中微子的比率及其能量谱，达到精确测量中微子混合角θ₁₃，使sin²2θ₁₃ 的精度在90%置信水平不低于0.01。 / 大亚湾实验一共有8 个反中微子探测器，放置在3 个实验大厅中。反中微子探测器的基本设计是3 层同心圆柱结构：最外层是高5 米直径5 米的不锈钢钢罐，中间有两个有机玻璃罐，直径分别为4 米、3 米，高度分别为4 米、3 米。最内的有机玻璃罐装有掺钆的液体闪烁体，作为探测中微子的靶物质。中间层处于4 米有机玻璃罐与3 米罐之间，装有普通液体闪烁体，用于收集掺钆液体闪烁体中产生的γ 光子能量沉积。最外层是透明的白油，主要用来屏蔽来自钢罐与192 只光电倍增管的天然放射。这些光电倍增管都是安装在钢罐上，浸没于白油中，由液体闪烁体放出的光子全都要经过白油才能被光电倍增管接收，所以，我们需要监测白油光学性质的变化，确保实验结果能够达到精度目标。 / 我们设计并完成一套自动监测光在白油中的衰减的系统。此系统利用一颗高功率发光二极管发出光脉冲，经过50 米的光纤进入反中微子探测器中。通过单光仪内置的步进马达，可以选择特定波长的光进行监测。在反中微子探测器的底部装有一个隅角棱镜，它能把光纤射出的光反射回探测器的顶部，使得光在白油中的传播长度倍增至8 米左右。反射回来的光被白油监测系统的2 英寸光电倍增管接收，信号再通过一个高速模数转换器处理。比较反射信号与参考信号的大小，就可以监测白油对光强的衰减随时间的变化。 / 在本篇论文中，我会详细介绍白油监测系统的设计过程与安装完成后实际运行，取数以及分析的情况。 / The Daya Bay reactor neutrino experiment aims at measuring the neutrino mixing angle θ₁₃ with a sensitivity of 0.01 or better in sin²2θ₁₃ at the 90% confidence level, through a measurement of the relative rates and energy spectra of reactor anti-neutrinos at different baselines. / There are eight anti-neutrino detectors (AD) deployed in three experimental sites. The AD has a three-zone cylindrical structure. Two acrylic vessels with diameter of 3 m and 4 m, and height of 3 m and 4 m respectively, are nested inside a 5m-diameter stainless steel vessel (SSV). The inner most volume, confined by the 3m-diameter inner acrylic vessel (IAV), is filled with Gadolinium doped liquid scintillator (GdLS), which acts as the neutrino target. The medium volume between the IAV and the 4m-outer acrylic vessel (OAV), is filled with normal liquid scintillator (LS) to capture gamma particles emitted from the target. The outer most volume is filled with transparent mineral oil (MO) which shields radiations from the steel or the 192 photo- multipliers (PMT) from entering the target. Since all the PMTs are mounted near the stainless steel wall of the SSV in the MO, the photons emitted by the liquid scintillator have to travel through MO before being detected by the PMT. It is crucial to monitor the optical properties of the MO for achieving the sensitivity of 0.01 in sin²2 θ₁₃. / We have designed and developed an automatic system for monitoring the light attenuation in the MO. The system utilizes a high power LED to send light pulses into the AD through a 50 m optical fiber. With the stepping motor driven monochromator, we can select several wavelengths in one monitoring run. There is a corner cube retro-reflector at the bottom of the AD, which reflects the light back to the top of the AD, thus doubling the light path in the mineral oil to around 8 m. The reflected light is received by the 2" PMT of the MO monitoring system and digitized by a flash ADC. By comparing the reflected and reference signals of the LED pulses, we can monitor the attenuation in the MO. / I will discuss the detailed design and performance of this MO monitoring system and data taken in the AD calibration runs. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Xiaocong = 應用於大亞灣中微子實驗的一套白油監測系統 / 陳瀟聰. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 106-108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Chen, Xiaocong = ying yong yu Daya Wan zhong wei zi shi yan de yi tao bai you jian ce xi tong / Chen Xiaocong. / Chapter 1 --- Introduction of the Daya Bay Reactor Neutrino Experiment --- p.1 / Chapter 1.1 --- Neutrino Oscillation --- p.1 / Chapter 1.1.1 --- The Discovery of Neutrino --- p.1 / Chapter 1.1.2 --- Oscillation Phenomenology --- p.3 / Chapter 1.1.3 --- Disappearance Probability --- p.4 / Chapter 1.2 --- the Daya Bay Reactor Neutrino Experiment --- p.6 / Chapter 1.2.1 --- Knowledge of the Oscillation Parameters Before Daya Bay --- p.6 / Chapter 1.2.2 --- Overview of the Daya Bay Experiment --- p.8 / Chapter 1.2.3 --- Layout of the Experimental Halls --- p.10 / Chapter 1.2.4 --- Antineutrino Detection --- p.12 / Chapter 1.2.5 --- Relative Measurements --- p.13 / Chapter 1.2.6 --- Significance of θ₁₃ --- p.14 / Chapter 1.2.7 --- The Antineutrino Detector --- p.15 / Chapter 1.2.8 --- Devices on the AD Lid --- p.17 / Chapter 1.3 --- Physics Result from the Daya Bay Experiment --- p.18 / Chapter 2 --- Design and Prototyping of the Mineral Oil Clarity Monitoring System --- p.20 / Chapter 2.1 --- Design --- p.20 / Chapter 2.1.1 --- Motivation of the Mineral Oil Clarity Monitoring System --- p.20 / Chapter 2.1.2 --- Attenuation of Mineral Oil --- p.24 / Chapter 2.1.3 --- MO Clarity Monitoring Scheme --- p.26 / Chapter 2.1.4 --- The Light Source for the MO Clarity Monitoring System --- p.28 / Chapter 2.1.5 --- Hardware inside the MO Clarity Box --- p.31 / Chapter 2.2 --- Prototyping of the Mineral Oil Clarity Monitoring System --- p.34 / Chapter 2.2.1 --- The Setup of the Prototype --- p.34 / Chapter 2.2.2 --- Stability Test of the Prototype --- p.36 / Chapter 2.2.3 --- Tolerance against the Deformation of the AD Lid --- p.39 / Chapter 2.2.4 --- Summary of the Tests on the Prototype --- p.40 / Chapter 3 --- Production and Installation of the Hong Kong Mineral Oil Clarity System --- p.42 / Chapter 3.1 --- Production and Component Tests --- p.42 / Chapter 3.1.1 --- Corner Cube Retroreflector --- p.42 / Chapter 3.1.2 --- Optical Fiber --- p.43 / Chapter 3.1.3 --- Calibration of the Monochromator --- p.45 / Chapter 3.1.4 --- Absolute Gain Measurement of the 2" PMT --- p.46 / Chapter 3.1.5 --- the Flash-ADC --- p.51 / Chapter 3.1.6 --- The Diffuser Ball --- p.53 / Chapter 3.2 --- Onsite Installation --- p.57 / Chapter 3.2.1 --- The Corner Cube --- p.57 / Chapter 3.2.2 --- Installation of the Acrylic Window and Leak Checking . --- p.58 / Chapter 3.2.3 --- Optical Alignment of the Collimator --- p.65 / Chapter 3.2.4 --- Cabling --- p.66 / Chapter 4 --- Operation of the MO Clarity Monitoring System --- p.68 / Chapter 4.1 --- Commissioning of the MO Clarity Monitoring System --- p.68 / Chapter 4.2 --- Data Processing --- p.70 / Chapter 4.2.1 --- Fitting of the PMT Waveforms --- p.71 / Chapter 4.2.2 --- Numerical Integration of the Peaks in the PMT Waveform --- p.75 / Chapter 4.3 --- EMI Pickup Problem --- p.79 / Chapter 4.4 --- MO Clarity Monitoring Results for the Eight ADs --- p.84 / Chapter 4.4.1 --- AD1 --- p.84 / Chapter 4.4.2 --- AD2 --- p.86 / Chapter 4.4.3 --- AD3 --- p.88 / Chapter 4.4.4 --- AD4 --- p.90 / Chapter 4.4.5 --- AD5 --- p.92 / Chapter 4.4.6 --- AD6 --- p.93 / Chapter 4.4.7 --- AD7 --- p.95 / Chapter 4.4.8 --- AD8 --- p.96 / Chapter 4.5 --- Comparison with Simulation Result --- p.98 / Chapter 4.5.1 --- Introduction of the NuWa Simulation --- p.98 / Chapter 4.5.2 --- Simulation Result with Displacement of the Optical Hole --- p.99 / Chapter 4.5.3 --- Possible Cause for the Large Uncertainty in the MO Monitoring Run for Some ADs --- p.100 / Chapter 4.6 --- Precision of the MO Monitoring System and Stability of the MO Attenuation Length --- p.102 / Chapter 5 --- Summary --- p.104 / Bibliography --- p.105
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328183 |
| Date | January 2013 |
| Contributors | Chen, Xiaocong, Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource ([2], xiv, 108 leaves) : ill. (some col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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