A study into the reconstruction of cascade like events in the IceCube neutrino detector was performed by utilizing in-situ flasher devices. Reconstruction analysis was done with two different flasher settings at each optical module on string 63 at varying depths in the ice. Three different reconstruction algorithms were used to estimate the characteristics of these cascade type events. The characteristics included the estimated vertex position, and the number of photons produced by each flasher. The number of photons produced can be related to the energy for the cascade event via the detailed knowledge of the cascade physics. Results from the analysis show the strengths of using the center of gravity type approaches to estimating the vertex positions of very bright events, and the inability to reconstruct to an accurate position in z which can occur when using more complicated vertex algorithms on the same events. Analysis using the energy reconstruction modules demonstrated the strengths of using methods that take into account the ice properties inside the detector.

Intermediate-degree g-modes (those with angular order ℓ ≈ 30) were first observed in the late 1970's by Hill and Caudell (1979). However, it wasn't until 1986 that a preliminary survey was made of the 1979 differential radius observations (see Bos 1982) and a set of 4 multiplets exhibiting mode-locking was classified by Hill (1986). These multiplets with angular order ℓ ≈ 30 and eigenfrequencies of ≈350 μHz were used as a starting point for the comprehensive analysis discussed in this work. This comprehensive study culminated in the classification of a set of 20 intermediate-degree g-mode multiplets containing over 600 normal modes of oscillation. Each of these multiplets was found to contain mode-coupled sections. Of more importance, however, are the internal properties of the Sun that can be inferred from this large body of classified modes. In this work two significant consequences will be discussed. Because these modes of oscillation are localized within the inner 50% of the Sun by radius and because of their large temperature eigenfunctions implied by the observed phase-locking, these modes of oscillation provide a modification of the effective temperature profile defined for a given process in the Sun. One of these processes is the ⁸B neutrino production. The second consequence of these observations is a predicted periodic modulation of the neutrino production rates. The existence of a large set of mode-coupled gravity modes will lead to a low-frequency modulation of neutrino production rates which may account for the observed periodicity in the ⁸B neutrino production (see Haubold and Gerth 1985). The prediction of this periodicity in the neutrino production rates is unique among all the competing theories that resolve the solar neutrino paradox and is testable by the new generation of solar neutrino detectors.

No description available.

The Sudbury Neutrino Observatory (SNO) was a 1 kilotonne heavy water Č{C}erenkov detector. Evidence for flavour changing neutrino oscillations was found by comparing the rate of Charged Current interactions with that of Neutral Current (NC) interactions. This thesis is concerned with the accurate determination of the NC flux in the Neutral Current Detector (NCD) phase of SNO. The measurement and understanding of radioactive backgrounds arising from decays of naturally occurring $^{232}$Th and $^{238}$U chain nuclei is crucial. This is because their daughter nuclei can produce neutrons via photodisintegration of deuterium. These would be indistinguishable from those produced by NC neutrino interactions. As the probability of neutron production was dependent upon the nature and location of activity, each contribution had to be determined separately. Of particular concern were $^{232}$Th and $^{238}$U in the D$_2$O and Neutral Current Detectors (NCDs). A maximum likelihood method was developed that exploited differences in the event isotropy and radial profile of each event class. These results were in agreement with water assay results and pre-deployment radioassays of the NCDs. An independent measurement of the $^{232}$Th content in the D$_2$O and H$_2$O was made by regularly assaying the water using filters loaded with hydrous titanium oxide. The concentration of $^{232}$Th in the water was determined by coincidence counting of the final assay sample. A new counter system was designed and built and the calibration and use of this system are presented. Two areas of increased activity were discovered on two of the NCDs deployed in the detector which would have prevented an accurate measurement of the NC flux. A method was devised to determine the composition and activity of one of these hotspots. The results were in good agreement with two independent methods and the uncertainty on the NC flux was reduced from $>7$% to $<1$%. The total number of neutrons produced per day by photodisintegration for $^{232}$Th and $^{238}$U in the D$_2$O and NCDs was measured to be $0.66^{+0.08}_{-0.07}$. This was significantly less than the expected 12.6 NC neutrino interactions per day. In the third phase, two independent data streams existed: PMT and NCD. A Monte Carlo study was undertaken to determine whether an accurate measure of the NC flux could be obtained using only PMT data. Results showed that no improvement could be made upon results from previous phases and the best measurement of the NC flux in the final phase would be made using PMT and NCD data.

We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, k(T) factorization including low-x resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 7TeV and at 13TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10% to 50% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.

Neutrinooszillation, ein Phänomen, das den Neutrino-Flavour nach ihrer Ausbreitung durch den Weltraum verändern kann, ist ein Beweis für nicht-verschwindende Neutrinomassen und ein Hinweis auf eine neue Physik außerhalb des Standardmodells. Diese Arbeit präsentiert die erste Messung zu atmosphärischen Neutrinooszillationen, die sechs Jahre zwischen Mai 2011 und Mai 2017 des IceCube DeepCore Experiment umfasst. Sie erweitert die bisher verfügbare Ereignisauswahl um eine neue Ereignissignatur und einen großeren Energiebereich. Diese Arbeit beschreibt die Methoden, die für die Simulationen der Wechselwirkungen der Neutrinos, die Ereignisauswahl, die Rekonstruktion und die statistische Behandlung von Messdaten und systematischen Messunsicherheiten benutzt werden. Die beste Abschätzung für die Neutrino-Mischungsparameter ist $\Delta m^2_{32} = 2.54^{+0.11}_{-0.12}\cdot 10^{-3}$~eV$^2$ und $\sin^2 \theta_{23} = 0.51\pm0.05$ (68\% C.L.) und gehört zurzeit zu den präzisesten Messungen atmosphärischer Neutrinos. Darüber hinaus wird in dieser Arbeit das Standard-Drei-Flavour-Modell überprüft, indem ein steriles Neutrino mit einer Masse in der Größenordnung von 1 eV eingeführt wird. Die Suche nach Effekten steriler Neutrinos auf atmosphärischen Neutrinooszillationen wird auf drei Jahren Daten, genommen zwischen Mai 2011 und Mai 2014, durchgeführt. Die Ergebnisse stimmen mit dem Standard-Modell der Drei-Neutrino-Oszillation überein, was zu den Obergrenzen für sterilen Neutrino-Mischungsparameter $|U_{\mu4}|^2<0.11$ und $|U_{\tau4}|^2<0.15$ (90\% C.L.) für $\Delta m^2_{41}=1$~eV$^2$ führt. Dieser Ergebnis ist derzeit die stringenste Obergrenze für $|U_{\tau4}|^2$. / Neutrino oscillations, a phenomenon that can change the flavour of neutrinos after their propagation through space, are a proof of non-zero neutrino masses and are an indication of new physics beyond the Standard Model. This work presents the first measurement of the atmospheric neutrino oscillations using six years of IceCube DeepCore data taken between May 2011 and May 2017. It extends the previously available event selection to include new event signatures and to use an extended energy range. This work discusses the techniques used for simulation of neutrino interactions, event selection, reconstruction, and the statistical treatment of data and systematic uncertainties. The best estimates for the neutrino mixing parameters are $\Delta m^2_{32} = 2.54^{+0.11}_{-0.12}\cdot 10^{-3}$~eV$^2$ and $\sin^2 \theta_{23} = 0.51\pm0.05$ (68\% C.L.), which are currently among the most precise measurements obtained with atmospheric neutrinos. In addition, this work tests the standard three-flavour paradigm by introducing one sterile neutrino with a mass on the order of 1~eV. The search for sterile neutrino effects in atmospheric neutrino oscillations is performed with three years of data taken between May 2011 and May 2014. The results are consistent with the standard three-neutrino oscillation picture, leading to limits on the allowed sterile neutrino mixing of $|U_{\mu4}|^2<0.11$ and $|U_{\tau4}|^2<0.15$ (90\% C.L.) for $\Delta m^2_{41}=1$~eV$^2$. Currently, the limit for $|U_{\tau4}|^2$ is the most stringent in the World.

El fenómeno de oscilaciones de neutrinos ha sido extensamente estudiado experimentalmente y teóricamente en las últimas décadas. Esto no sólo implicó su confirmación sino también la medida de casi todos los parámetros asociados a ésta. Sin embargo, aún quedan pendientes algunas incógnitas por resolver como son la jerarquía de las masas de los neutrinos, la determinación de la fase que viola la simetría carga-paridad, el problema de las degeneraciones, entre otras. Para poder ser resueltos muchos de estos problemas requieren experimentos de gran escala y con la más óptima tecnología para la detección de neutrinos. El experimento DUNE (Deep Underground Neutrino Experiment) tendrá estas capacidades. Este experimento tiene una distancia fuente – detector de 1300km contando con un detector cercano de alta precisión y uno lejano de 40 kton hecho de Argón Líquido. Estas características no sólo permitirán resolver los problemas mencionados sino que además permitirán estudiar, por ejemplo, neutrinos provenientes del colapso de supernovas, así como el decaimiento del protón, entre otros procesos. En esta tesis se ha realizado una revisión detallada de la física de oscilación de neutrinos tanto en vacío como en materia, incorporando a este último el decaimiento invisible de neutrinos. Este fenómeno aunque descartado hoy para la explicación del problema de los neutrinos solares y atmosféricos. Tiene Actualmente una relevancia como un efecto subdominante dentro de las oscilaciones de neutrinos. Haciendo que la probabilidad de oscilación sufra un amortiguamiento. En esta tesis estudiaremos la sensibilidad de DUNE al nuevo parámetro que corresponde al decaimiento invisible de neutrinos. Viendo como distintos valores de este parámetro modifican el espectro de energía producido por los eventos que se observarían en DUNE. Nuestras simulaciones han sido hechas utilizando el paquete GLoBES (General Long Baseline Experiment Simulator) y usando como datos de entrada inputs, distribuciones proporcionadas por el propio experimento. / Tesis

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

This thesis will present a search for sterile neutrinos using data taken with the MINOS experiment between 2005 and 2012. MINOS is a two-detector on-axis experiment based at Fermilab. The NuMI neutrino beam encounters the MINOS Near Detector 1km downstream of the neutrino-production target before travelling a further 734km through the Earth's crust, to reach the Far Detector located at the Soudan Underground Laboratory in Northern Minnesota. By searching for oscillations driven by a large mass splitting, MINOS is sensitive to the existence of sterile neutrinos through looking for any energy-dependent perturbations using a charged-current sample, as well as looking at any relative deficit in neutral current events between the Far and Near Detectors. This thesis will discuss the novel analysis that enabled a search for sterile neutrinos covering five orders of magnitude in the mass splitting and setting a limit in previously unexplored regions of the sterile neutrino parameter space, where a 3+1-flavour phenomenological model was used to extract parameter limits. The results presented in this thesis are sensitive to the sterile neutrino parameter space suggested by the LSND and MiniBooNE experiments.

No description available.