Two aspects of the problems encountered in searching for nucleon decay in the Soudan 2 detector are discussed. The types of event which are expected are discussed. The most common are Induced by gamma rays from the naturally occurring radioactive isotopes in the cavern rock. A calculation has been developed to predict the rates of such events in the detector and the results agree well when compared with measurements made underground. Some radioactive events cause Compton scattering in the wireplane region of the detector and prohibit the use of a simple multiplicity trigger. Such events have been studied. An electronic trigger system has been designed which will achieve a factor of 10³ rejection of these events while remaining efficient for even the most difficult modes of proton decay (75% for p -> K ⁺V ). It is predicted that radioactive triggers will occur at less than 3Hz when the full detector is operating. The neutrino induced background to proton decay has been simulated. The neutrino flux at the detector caused by cosmic ray induced showers in the atmosphere has been predicted. A comprehensive low energy (0.2 GeV to 20 GeV) Monte-Carlo neutrino event generator has been developed as a tool for background studies to proton decay. The Teinteraction of proton decay or neutrino interaction products in the parent nucleus is discussed. It is found that these reinteractions are quite probable, except for K⁺ and K° particles. Data from a low energy neutrino beam experiment has been studied and it is deduced that in some cases, the events seen in the detector will contain visible tracks associated with the disintegration of the parent nucleus. A background estimate for the mode p ➝ K⁺V from the neutrino interaction Vn ➝ μ~p is presented.

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

Principles of beam dump experiments are reviewed and the 1982 beam dump at CERN using the Big European Bubble Chamber is described in detail. Neutrino events have been detected using both the bubble chamber and its associated electronic detectors. Prompt event rates are established for V_μ , Ṽ_μ , V_e and Ṽ_e . The prompt rates are consistent with lepton universality. The charm production cross-section required to explain the prompt electron-(anti)neutrino signal is approximately 16-105/μb per nucleon, assuming linear dependence of this cross-section on nucleon number. This range of values reflects the fact that we have not been able to find a model which is consistent with all aspects of the data. The neutral to charged current ratio for electron-neutrinos is found to be 0.23 ±0.16. The expected number of tau-neutrino events is estimated and kinematic and visual searches for tau-neutrino interactions are described. One visually detected candidate is described in detail. No positive evidence for a tau-neutrino interaction has been found. From the ratio of neutral to charged current events in the data we infer that no more than 4% of the prompt charged current events and 40% of the total prompt signal may be attributed to tau-neutrinos at 90% CL.

The HERA accelerator, an electron-proton collider facility based at the DESY laboratory in Hamburg, started delivering luminosity to the ZEUS experiment in May 1992. The short time of 96ns between bunch crossings and the fact that the primary source of detector activity in ZEUS does not come from the e-p interactions of interest but rather from other sources makes a high performance three level trigger system essential to data-taking. We present one part of the ZEUS trigger system, the Central Tracking Detector First Level Trigger (CTD-FLT). The principle of operation and the hardware implementation are discussed at length. A prototype system which was used during the early stages of ZEUS data-taking is described. We detail the principles of the CTD-FLT hardware testing and discuss aspects of the First Level Trigger data from the 1993 running period. During this time the CTD trigger has proved to be an invaluable part of the overall system. The high energies accessible at HERA make it possible to probe a variety of new physics models. The second part of this thesis focuses on one such model - Supersymmetry (SUSY). After an introduction to the model, a search for R-parity violating SUSY in the ZEUS data from the 1992 running period is described. No evidence for such signals has been found and hence we set upper limits on the mass scale of the theory. Finally we present a Monte Carlo study of the potential discovery reach of HERA for R-parity violating SUSY models, and come to the conclusion that HERA is an ideal place to look for such phenomena.

The search for physics beyond the Standard Model has been a main focus of the scientific community for several decades. Unknown physics in the form of new interactions violating the simultaneous reversal of charge and parity symmetries (CP) would, for example, provide a significant step towards understanding the baryon matter-antimatter asymmetry observed in the Universe. Such parameters are predicted to also manifest themselves in atomic and molecular systems in the form of both: permanent electric dipole moments and nuclear charge distribution asymmetries described by the nuclear Schiff moment. Both can be measured to a high degree of precision in modern experiments, allowing us to place stringent limits on parameters appearing in new fundamental theories. The Cold Molecule Nuclear Time Reversal Experiment (CeNTREX) is the latest approach to probing these effects. CeNTREX is a molecular beam experiment that uses thallium fluoride (²⁰⁵Tl⁹F) as its test species to measure energy shifts induced by the interaction of thallium's nuclear Schiff moment. It does so by performing nuclear magnetic resonance using a separate oscillatory fields technique. The precision of this measurement is dictated by the free precession time and the number of interrogated molecules, and is significantly enhanced by thallium fluoride's inherent properties. Employing novel methods, CeNTREX strives to achieve significant improvements to limits placed on the fundamental parameters. One such method is rotational cooling. It was thoroughly analyzed, simulated and experimentally confirmed - with the help of optical and microwave pumping, we collapsed the initial Boltzmann distribution of molecules amongst their rotational states into one chosen hyperfine state of the ground rotational state manifold. The efficiency of this process depends on multiple factors, the most crucial being the approach towards dark state destabilization and remixing. After careful investigation, we chose the most appropriate method and devised an efficient rotational cooling scheme. Experimental confirmation showed an enhancement factor of r𝑓23.70±1.13, very close to our theoretical predictions. This allows us to conclude that CeNTREX should provide a 2500-fold improvement over the current best measurements of the nuclear Schiff moment in thallium nucleus.

This thesis describes an analysis of the process e⁺e^— → l⁺l^- (where l = e, μ,, τ) at centre-of-mass energies between 88 GeV and 94 GeV, using the data collected by the DELPHI detector between the years 1991 and 1993. The leptonic decays of the Z° boson are selected without attempting to separate the three lepton types, thus making it an inclusive lepton analysis. The theory behind lepton pair production is introduced and the extraction of various electroweak parameters from the experimental observables is discussed. The LEP collider and the DELPHI detector are described, with special emphasis being given to the sub-detectors used in the analysis. The criteria used to select a high purity leptonic sample are described along with calculations of various backgrounds and efficiencies. The sample of selected leptonic events is then used to measure the cross-sections and forward-backward asymmetries. Finally, a fit to these cross-sections and asymmetries, together with the hadronic (e⁺e^- → qq̄) cross-sections, is carried out. Various Z° parameters are obtained: the mass and total width Mz-91.1876 ± 0.0052 GeV/c², Γ_z = 2.4971 ± 0.0061 GeV, the ratio of the hadronic to leptonic partial widths R_l = 20.73 ± 0.09, and the pole leptonic asymmetry (A°_FB)¹ = 0.0195 ± 0.0042. Using these results and the value of the strong coupling constant (α_s), determined by the DELPHI collaboration, the number of light neutrino species is determined to be N_ν = 3.045 ± 0.035. The leptonic partial width is found to be: Γ_l = 83.82 ± 0.29 MeV. Using the measured leptonic forward-backward asymmetries, the squared vector and axial-vector couplings of the Z° to charged leptons are found to be (ĝ_v¹)^{2</sup = (1.65 ± 0.36) x 10^-3 and (ĝ_a¹)}2</sup> = 0.2505 ± 0.0009. These values can be used to determine the effective rho parameter and the effective weak mixing angle: p̂ = 1.0020 ± 0.0036, and sin² θ^eff_lept = 0.2297 ± 0.0024. A full Standard Model fit to the data gives the values of the strong coupling constant, α_s, and the mass of the top quark, m_top, as being: α_s = 0.123 ± 0.010, m_top = 178⁺²²_-25 (expt)<sup>+18<sup>_-16(Higg s)GeV/c², where 60 < m_Higgs (GeV/c²) < 1000 with a central value of 300 GeV/c². All the results obtained agree with the results from the lepton-identified analyses (analyses in which leptonic events are selected on the basis of their individual flavour) and with the predictions of the Standard Model.

We present results from Fermilab MPS experiment E580 on the reactions π⁻N->V°X where V° is K°_S, A or A̅ and X are charged particles. Transverse and longitudinal momentum distributions for the V° and for K*^±(892), Σ^±(1385), Ξ⁻(1321) and Ξ⁺(1321) are presented. A comparison is made with the prediction of QCD quark counting rules. Evidence for A⁺_C; is presented. / Ph. D.