Ngai Wah Kai = 中微子混合角[theta]₁₃測量的最優化與本底研究 / 魏華佳. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 83-87). / Text in English; abstracts in English and Chinese. / Ngai Wah Kai = Zhong wei zi hun he jiao [theta]₁₃ ce liang de zui you hua yu ben di yan jiu / Wei Huajia. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Puzzle with Beta Decay Spectrum --- p.2 / Chapter 1.2 --- Detection of a Free Neutrino --- p.3 / Chapter 1.3 --- Properties of Neutrinos --- p.5 / Chapter 1.3.1 --- Neutrino Mass --- p.6 / Chapter 1.3.2 --- Dirac and Majorana Neutrinos --- p.7 / Chapter 1.3.3 --- Neutrino Oscillation --- p.8 / Chapter 1.4 --- Background to Underground Neutrino Experiments --- p.10 / Chapter 1.5 --- Outline of the Thesis --- p.12 / Chapter 2 --- The Last Mixing Angle and Daya Bay --- p.14 / Chapter 2.1 --- Current Status of Neutrino Oscillation --- p.14 / Chapter 2.2 --- Measurement of θ13 with Reactors --- p.19 / Chapter 2.3 --- "Daya Bay, the Site and the Detector" --- p.20 / Chapter 2.3.1 --- Overview --- p.20 / Chapter 2.3.2 --- Detector --- p.22 / Chapter 3 --- Detector Baseline Optimization --- p.24 / Chapter 3.1 --- Antineutrino Spectrum and Flux from Reactors --- p.25 / Chapter 3.1.1 --- Antineutrino Production --- p.25 / Chapter 3.1.2 --- Antineutrino Spectrum from Reactors --- p.26 / Chapter 3.2 --- Interaction Rate Analysis --- p.29 / Chapter 3.3 --- Spectral Analysis --- p.30 / Chapter 3.3.1 --- Effect of Three-Neutrino Mixing --- p.33 / Chapter 4 --- Energy Resolution of the Proposed Antineutrino Detector --- p.37 / Chapter 4.1 --- Physical Processes inside the Detector --- p.38 / Chapter 4.2 --- Simulation Algorithm --- p.39 / Chapter 4.3 --- Comparison of Different Detector Geometries and Configurations --- p.43 / Chapter 5 --- Aberdeen Tunnel Laboratory - A Satellite Lab of Daya Bay --- p.53 / Chapter 5.1 --- Geological Properties --- p.54 / Chapter 5.2 --- Research Plan and Methodology --- p.55 / Chapter 5.2.1 --- Detector Configuration --- p.55 / Chapter 5.2.2 --- Front-End Electronics --- p.58 / Chapter 5.2.3 --- Trigger System --- p.60 / Chapter 6 --- Cosmic Ray Muons and Induced Neutron Underground --- p.63 / Chapter 6.1 --- Background to Reactor Antineutrino Experiments --- p.63 / Chapter 6.1.1 --- Origins of the Fast Neutrons --- p.64 / Chapter 6.2 --- Muon Flux and Energy Spectrum Underground --- p.65 / Chapter 6.2.1 --- Muons at the Earth Surface --- p.66 / Chapter 6.2.2 --- Propagating Muons through Rock --- p.67 / Chapter 6.2.3 --- Flat Surface Case --- p.69 / Chapter 6.2.4 --- Aberdeen Mountain Case --- p.69 / Chapter 6.2.5 --- Pyramid Case --- p.72 / Chapter 6.2.6 --- Daya Bay Case --- p.73 / Chapter 6.3 --- Predicting Neutron Production from Cosmic Ray Muons --- p.76 / Chapter 6.3.1 --- Neutron Yield --- p.77 / Chapter 6.3.2 --- Neutron Energy Spectrum --- p.79 / Chapter 6.3.3 --- Neutron Angular Distribution --- p.80 / Chapter 6.3.4 --- Neutron Multiplicity --- p.81 / Bibliography --- p.83 / Chapter A --- Three-neutrino mixing formula --- p.88 / Chapter B --- Sea Level Muon Generator --- p.90 / Chapter B.1 --- Acceptance-rejection Method --- p.90 / Chapter B.2 --- Finding the Comparison Functions --- p.91 / Chapter B.3 --- Checking the Generator --- p.92 / Chapter C --- Circuit Diagrams of the Discrimination Board for Plastic Scintillators --- p.96

In this thesis, we investigate observable consequences of active and sterile neutrinos, in galactic, cluster, and cosmological scales. We assume that sterile neutrinos with masses of order 10's eV, 10's keV, and MeV were formed by oscillation of active neutrinos in the early universe. If sterile neutrinos with mass ∼ 30 eV exist, they affect the structure of galaxies and explain the flatness of their rotation curves. Also, the existence of decaying sterile neutrinos with mass 16 --- 18 keV and decay rate Gamma = (5 +/- 1) x 10--17 s--1 can simultaneously be the cause of heating at the Milky Way center, the supermassive blackhole mass and velocity dispersion relation, the lack of cooling flow in clusters, and reionization in the universe. Lastly, we make use of the observed 511 keV annihilation flux line at the Milky Way center to constrain properties of sterile neutrinos of MeV mass scale. We also derive a relation among several cluster observables assuming the existence of an active neutrino halo, which agrees with the observational data in 103 clusters. / Chan, Man Ho = 中微子天文物理 / 陳文豪. / Adviser: Ming-Chung Chu. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: December, 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 107-113). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307. / Chan, Man Ho = Zhong wei zi tian wen wu li / Chen Wenhao.

We studied dimuon events arising from trident production, for both coherent and incoherent processes, as well as relevant backgrounds, in order to predict the number of expected events observed in the lifetimes of current and forthcoming neutrino experiments. In particular, for this thesis, we focused in building the implementation of the incoherent contribution within the context of the GENIE montecarlo generator. We also developed relatively detailed GEANT4 geometries for the MINERvA detector as well as the DUNE Near Detector, for the Liquid Argon (LArTPC) and Straw Tube Tracker (STT) proposals. A very careful study of the backgrounds for the incoherent case was carried, in order to complement the study already done for the coherent contribution. Then, we combined the signals for the coherent and incoherent processes to realize a more realistic study of the expected number of events. The ROOT TMVA package for multivariate analysis was then used to filter signal from background. The results are presented in terms of number of events, and are calibrated based on the detector exposure in the lifetime of the MINERvA detector and DUNE Near Detector. / Tesis

Orientador: Vicente Pleitez / Doutor

Graduation date: 2000

While confirmations of the validity of the Standard Model at low and high energies (reached by present accelerators) continue to be produced, the high-energy physics community is turning towards the search for physics beyond the Standard Model. In chapter 2 we review the evidence for the existence of three neutrino flavors. We proceed by quickly summarizing their properties in the Standard Model and examine the present limits set by experiments on each neutrino's mass. We then move on to some theoretical considerations on neutrino masses, mainly based on cosmology and Grand Unified Theories and the chapter closes by illustrating the remarkable possibility of neutrino oscillations. Interestingly, at the end of 1997 it is in the neutrino physics domain that most inconsistencies with the Standard Model are found. Not in experiments using neutrinos to study the weak and strong interactions, as we see at the start of chapter 3, but definitely when probing the solar and atmospheric neutrino fluxes. This is detailed later in that chapter, without forgetting the only neutrino oscillation appearance evidence found so far (LSND). From the results presented it seems to be clear that neutrinos have opened a window towards new physics. However, solving all the present problems (cosmology, solar, atmospheric, LSND) with our simple neutrino oscillation interpretation seems impossible or difficult and definitely not very elegant. So maybe this window we are opening is really much larger than we think and pushing more could yield some fascinating results. The existing constraints are definitely such that experiments should be built to search for appearance at specific oscillation parameter values. When Chorus was designed and started datataking, these constraints were quite a bit weaker. However, the parameter space area which is being explored is still very relevant in the light of a model solving the Hot Dark Matter and solar problems while satisfying the very elegant see-saw mechanism. We briefly describe the experiment in chapter 4, explaining the chosen tau neutrino detection strategy and the proposed sensitivity to Vµ -> Vtau oscillations. In chapter 5 we start by describing the trackers: purpose, geometry and readout. This is followed by an explanation of the event reconstruction algorithm and its efficiency. Our main contribution to the reconstruction in the Target Trackers consists in their alignment: after introducing a few concepts we give the details of the alignment procedure, the trackers' degrees of freedom and the accuracy obtained for each of these. Two more paragraphs say a few more words on the problem of separation of variables for minimization and the detector stability over time. Next, in chapter 6, we discuss our work on the tagging of muons with the Chorus detector. After explaining the various algorithms used we come to the efficiencies, understanding the found results through event kinematics. A study of non-tagged muons shows that the software efficiency is very close to maximal, and physics is the cause of nearly all the losses. The bulk of our study lies in the determination of the scanning efficiencies. Chapter 7 starts with the description of the interface emulsion sheets and the proof of a method we developed to extract the real scanning efficiency for these sheets from the data itself. We proceed to compare the found results with the results obtained by our simulation and comment on the possible causes for the observed discrepancy. Moving on, we explain how the search for the primary vertex and a possible decay kink is conducted and give the corresponding efficiencies we found using our Monte-Carlo. To close the chapter, we elaborate on the video image simulation, a tool we developed to help improve and determine the efficiency of video image analysis programs. These programs will be used intensively in the future to search for kinks. Last but not least, chapter 8 combines all these numbers with the present scanning status to put a new limit on Vµ -> Vtau oscillations. It also includes a few words on backgrounds and the results from a study of systematic uncertainties. We conclude with a new exclusion plot.

Thèse de doctorat : Physique. Physique des particules : Strasbourg : 2009. / Thèse soutenue sur un ensemble de travaux. Titre provenant de l'écran-titre. Bibliogr. 6 p.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 407-419).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 53-56). Available also in a digital version from Dissertation Abstracts.

Using the NEMO-3 detector, 410.4 g of ¹¹⁶Cd with a total exposure of 1.65 kg• y and 932 g of ⁸²Se with a total exposure of 3.75 kg• y were used to measure the half-life of two-neutrino double beta decay (2[nu][beta][beta]) to the ground states of ¹¹⁶Sn and ⁸²Kr and to place a lower limit on the neutrinoless double becay decay (0[nu][beta][beta]) to the same ground states. Under the single-states dominance hypothesis, the 2[nu][beta][beta] half-lives are found to be T 1/2(¹¹⁶Cd) = (2.90 ± 0.03(stat) ± 0.15(syst)×10¹⁹ yr and T 1/2(⁸²Se) = [10.62±0.11(stat)±0.56(syst)]×10¹⁹ yr. 0[nu][beta][beta] is excluded to 90% confidence level at T 1/2 ≥ 1.12 × 10²³ yr for ¹¹⁶Cd and T 1/2 ≥ 3.90 × 10²³ yr for ⁸²Se. These half-lives correspond to effective Majorana neutrino masses of m ≤ (4.33 - 5.54) eV and m ≤ (2.28 - 2.82) eV, respectively, in the light Majorana exchange mechanism. / text