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.

There was recently introduced into the secondary schools of British Columbia a course in physics based primarily upon the work of the Physical Science Study Committee. At the end of the course a study is made of atomic physics. A fundamental concept involved in the study of atomic physics is that of the quantum of light energy. A photocell experiment suitable for use in secondary schools has been developed which is intended to help the student to come to major conclusions regarding the photoelectric effect and the nature of light. In developing this experiment investigations were made to determine the suitability of available apparatus and methods. Among the aspects investigated were photocells, light sources, filters, methods of measuring small currents, and methods of investigating the photoelectric effect. The experiment which evolved was then performed under conditions more suitable than exist in secondary schools. The results of the experiment agreed with the major points of the theory and yielded a value for Planck's constant within ten per cent of accepted value. It was concluded that a photocell experiment can be performed in secondary schools which will yield results which agree with the theory. / Education, Faculty of / Graduate

Call number: LD2668 .T4 1938 G51

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.

Acompanha: Ensino da física e aprendizagem significativa: roteiro para a elaboração de uma aula / O presente estudo teve como objetivo propor um roteiro para a elaboração de uma aula significativa. Do ponto de vista metodológico, por visar o desenvolvimento de um produto, o estudo caracteriza-se como aplicado e de natureza prática. Observou-se, na montagem do produto, a sequências das etapas para sua construção e aspectos relacionados com sua validade e possibilidade de utilização por outros docentes como uma ferramenta de ensino. O “roteiro para a elaboração de uma aula” foi estruturado em seis etapas principais, definição do conteúdo da aula, determinação dos aspectos mais relevantes do conteúdo e dos organizadores prévios, sequenciação do conteúdo curricular, avaliação da aprendizagem, estratégia e recursos instrucionais e montagem do plano de aula. Em cada etapa foram estabelecidas as atividades a serem cumpridas. Concluí-se que o roteiro proposto é uma ferramenta que tem alinhamento com a teoria de Ausubel, o que possibilita a montagem de uma aula significativa. / The current study had as a goal to purpose a guide for building a meaningful class. From the methodological point of view, by targeting the development of a product, the study characterized as applied and practical. It was observed, during assembly of the product, the sequences of steps for its construction and aspects related to its validity and possibility of being used by other lecturers as a teaching tool. The “guide for the elaboration of a class” was structured in six main steps, namely, definition of the class content, determination of the most relevant aspects from the content and from the previous organizers, sequencing of curriculum content, knowledge evaluation, strategy and instructional resources and lesson plan assembly. In each step were established the activities to be accomplished. It is concluded that the purposed script is a tool that has alignment with the Ausubel theory, allowing the composition of a substantial class.

Acompanha: Ensino da física e aprendizagem significativa: roteiro para a elaboração de uma aula / O presente estudo teve como objetivo propor um roteiro para a elaboração de uma aula significativa. Do ponto de vista metodológico, por visar o desenvolvimento de um produto, o estudo caracteriza-se como aplicado e de natureza prática. Observou-se, na montagem do produto, a sequências das etapas para sua construção e aspectos relacionados com sua validade e possibilidade de utilização por outros docentes como uma ferramenta de ensino. O “roteiro para a elaboração de uma aula” foi estruturado em seis etapas principais, definição do conteúdo da aula, determinação dos aspectos mais relevantes do conteúdo e dos organizadores prévios, sequenciação do conteúdo curricular, avaliação da aprendizagem, estratégia e recursos instrucionais e montagem do plano de aula. Em cada etapa foram estabelecidas as atividades a serem cumpridas. Concluí-se que o roteiro proposto é uma ferramenta que tem alinhamento com a teoria de Ausubel, o que possibilita a montagem de uma aula significativa. / The current study had as a goal to purpose a guide for building a meaningful class. From the methodological point of view, by targeting the development of a product, the study characterized as applied and practical. It was observed, during assembly of the product, the sequences of steps for its construction and aspects related to its validity and possibility of being used by other lecturers as a teaching tool. The “guide for the elaboration of a class” was structured in six main steps, namely, definition of the class content, determination of the most relevant aspects from the content and from the previous organizers, sequencing of curriculum content, knowledge evaluation, strategy and instructional resources and lesson plan assembly. In each step were established the activities to be accomplished. It is concluded that the purposed script is a tool that has alignment with the Ausubel theory, allowing the composition of a substantial class.

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.

An abundance of evidence from a wide range of astrophysical and cosmological observations suggests the existence of nonluminous cold dark matter, which makes up about 83% of the matter and 27% of the mass-energy of the Universe. Weakly Interacting Massive Particles (WIMPs) have been one of the most promising dark matter candidates. Various detection techniques have been used to directly search for the interaction in terrestrial detectors where WIMP particles are expected to scatter off target nuclei. Over the last fifteen years, dual-phase time projection chambers (TPCs) with liquid xenon (LXe) as target and detection medium have led the WIMP dark matter search. The XENON dark matter search project is a phased program focused on the direct detection of WIMPs through a series of experiments employing dual-phase xenon TPCs with increasing target mass operated at the Gran Sasso underground laboratory (LNGS) in Italy. The XENON1T experiment is the most recent generation, completed at the end of 2018. The XENON1T dark matter search results from the one ton-year exposure have set the most stringent limit on the WIMP-nucleon spin-independent elastic scatter cross-section over a wide range of masses, with a minimum upper limit of 4.1 x 10⁻⁴⁷ cm² at 30 GeV · c⁻² and a 90% confidence level. XENON1T is the first WIMP dark matter experiment which has deployed a dual-phase xenon TPC at the multi-ton scale, with 3.2 t of LXe used. The large xenon mass posed new challenges in reliable and stable xenon cooling, in achieving and maintaining ultra-high purity as well as in efficient and safe xenon storage, transfer and recovery. The Cryogenic Infrastructure was designed and constructed to solve these challenges. It consists of four highly interconnected systems --- the Cryogenic System, the Purification System, the Cryostat and Cryogenic Pipe, and the ReStoX System. The XENON1T Cryogenic Infrastructure has performed successfully and will continue to serve the next generation experiment, called XENONnT, with a new Cryostat containing a total of 8.4 tons of xenon. I first give an instrument overview of the systems in XENON1T. I then review the cooling methods in LXe detectors which led to the design of the cooling system implemented in the XENON1T experiment, and suggest a design of the cooling system for future LXe dark matter experiments at the 50 tons scale. I describe and discuss in detail the design and the performance of the XENON1T Cryogenic Infrastructure. Finally, I describe the detector stability and the corresponding data selection in all three XENON1T science runs, and describe the dark matter search results from the one ton-year exposure.