Dark Matter (DM) is believed to consist ofWeakly Interactive Massive Particles (WIMPs) which interact only through gravity and the weak nuclear force. These particles can become trapped in gravitational wells such as the Sun and a theoretical value of the capture rate can be calculated. At high particle density the WIMPs annihilating spontaneously into Standard Model (SM) particles. Due to particle equilibrium the total annihilation rate can be related to the capture rate by a simple expression. This report will focus on calculating the capture rate and the related annihilation rate as well as calculating the neutrino 　ux of the Sun. At rst we will give a brief introduction to cosmology and a theoretical argument for the WIMPs as the prime DM candidate. Then we will look at the theoretical background and the mechanism through which WIMPs become trapped and evaporate or annihilate. Finally we will perform a numerical analysis of the WIMP cycle within the Sun and calculate the capture rate for a variety of theoretical WIMP masses. We will look at the capture rate due to scattering both by hydrogen nucleii and by more massive elements. The Scattering by hydrogen will be the prime contributor to the total capture rate and is the only spin dependent contribution.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19500号 / 理博第4160号 / 新制||理||1597(附属図書館) / 32536 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中家 剛, 教授 谷森 達, 准教授 市川 温子 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

No description available.

Neutrino physics has been going through rapid developments since the particle was first proposed by Pauli. The observation of neutrino oscillations has prompted an investigation of the issue of neutrino mass, with the "seesaw" mechanism garnering theoretical support. The HUNTER (Heavy Unseen Neutrinos from the Total Energy-momentum Reconstruction) experiment brings together AMO, nuclear physics and high energy physics researchers from Temple University, Houston University, UCLA and Princeton University to develop an apparatus capable of probing the keV-mass range of sterile neutrinos with high precision. The HUNTER detector makes use of the well-established COLTRIMS techniques for the collection of all the decay products of a neutrino-producing decay, and the reconstruction of their initial momenta and energies. Energy and momentum conservation allow then for the reconstruction of the missing neutrino mass.Electrons produced in the decay are guided towards their detector by an optimized set of electrodes paired to a magnetic field to confine their trajectories into spirals. A magnetic shield protects the electron from external stray fields that could alter their trajectories. A thorough study on the main source of background, namely the source scattering of ions, was conducted. As an additional topic, the feasibility of a directional-sensitive dark matter search experiment has been studied. Simple models of galactic dark matter distribution suggest that the motion of the Earth in space might introduce a directional anisotropy in the WIMPs momentum distribution at the Earth. The shape of a WIMP-like recoil in a target material could be be used to extract directional information for the incident WIMP, and thus confirm the anisotropy. The peculiar microphysics of liquid Argon requires thermalization of ionization electrons for a signal to form. To determine if directional information can be extracted, one needs to understand the energy spectrum of the electrons emitted in recoil event. Then, one needs a model to determine the time scale of the thermalization, and the distance to which the electrons travel. / Physics

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24406号 / 理博第4905号 / 新制||理||1701(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中家 剛, 准教授 WENDELL Roger, 教授 永江 知文 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

No description available.

The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment was designed to probe short baseline oscillations of electron antineutrinos in search of eV-scale sterile neutrinos and precisely measure the 235U reactor antineutrino spectrum from the High Flux Isotope Reactor (HFIR) at Oak Ridge national Laboratory (ORNL). The PROSPECT antineutrino detector (AD) provided excellent background rejection due to its segmented design and use of 6Li-loaded liquid scintillator for a neutron capture target. By tracking the neutron capture lifetime from cosmogenic neutrons and a 252Cf neutron source, we suspect the 6Li content of our scintillator changed over time. We look at this evolution and uncertainty in the PROSPECT oscillation and spectrum analyses. Additionally, the 252Cf source data taken with the PROSPECT AD for detector calibrations are used to make a new measurement on the neutron multiplicity probability distribution emitted during spontaneous fissions, with an average multiplicity of 3.81 ± 0.05 neutrons per fission. / Physics

In this thesis we consider a number of past, present, and future neutrino experiments designed to test physics beyond the Standard Model. First, we analyze potential new physics explanations of the NuTeV anomaly and check their compatibility with the most recent experimental data. The models we consider are: gauged Lmu-Ltau, gauged B-3Lmu, and S1, S3, V1, V3 leptoquarks. We find that only the triplet leptoquark models can explain NuTeV and be compatible with the data from other experiments at the same time, and only if the components of the triplet have different masses. Then, we analyze the prospects of discovery of heavy Majorana neutrinos (neutrissimos) suggested by the Okamura model at the LHC. We find that these particles, if produced, will live short enough to decay inside of the detector, while long enough to lead to a narrow peak in the invariant mass spectrum of the decay products. We estimate the typical masses of the neutrissimos to be in the TeV range. However, studies exist that have shown that if their masses are larger than about 150 GeV then the production cross-section is too small to lead to an observable event rate. Thus, we conclude that it will not be possible to detect the neutrissimo at the LHC unless its mass is smaller that about 150 GeV which corresponds to a very small region close to the edge of the parameter space of the Okamura model. Nevertheless, we argue that the signature of the neutrissimo may be detectable in other neutrino experiments which may be carried out in the future. As examples, we consider the NuSOnG experiment, which is a fixed target neutrino scattering experiment proposed at Fermilab, and a hypothetical long-baseline neutrino oscillation experiment in which the Fermilab NUMI beam is aimed at the Hyper-Kamiokande detector in Japan. In addition to the sensitivity to neutrissimos, we analyze the capabilities of these experiments to constraint the coupling constants and masses of new particles in various models of new physics suggested in the literature. The models we consider are: neutrissimo models, models with generation distinguishing Z's such as topcolor assisted technicolor, models containing various types of leptoquarks, R-parity violating SUSY, and extended Higgs sector models. In several cases, we find that the limits thus obtained could be competitive with those expected from direct searches at the LHC. In the event that any of the particles discussed here are discovered at the LHC, then the observation, or non-observation, of these particles in the NuSOnG and Fermilab-to-Hyper-Kamiokande experiments could help in identifying what type of particle had been observed. / Ph. D.

In this thesis we analyze a number of past, current, and future experiments to extract information on physics beyond the Standard Model. We use the Jacobi method to derive a set of simplified expressions for the probabilities of neutrino oscillations in matter. we show the possible constraints that can be placed on various models beyond the Standard Model. In several cases, we find that the limits thus thus obtained could be competitive with those expected from direct searches at the Large Hadron Collider. We then consider the possible effects of new physics beyond the Standard Model on precision measurements. In particular, we look at recent Bell/Babar results on the B meson branching fraction, and the bounds on Tau-decays from Babar. As a general framework of analyzing new physics beyond the Standard Model, we discuss what constraints can be placed on R-parity violating SUSY from these experiments. To complete our analysis, we update the single-coupling bounds on R-parity violating supersymmetry using the most up to date data as of October 2009. In addition to the data listed in the latest Review of Particle Properties, we utilize a new measurement of the weak charge of cesium-133, and preliminary Tau-decay branching fractions from Babar. Analysis of semileptonic D-decay is improved by the inclusion of experimentally measured form-factors into the calculation of the Standard Model predictions. / Ph. D.

The Daya Bay reactor neutrino experiment is a high sensitivity experiment designed to determine the last unknown neutrino mixing angle $theta_{13}$ by measuring disappearance of reactor antineutrinos emitted from six 2.9 $GW_{th}$ reactors at the Daya Bay Nuclear Power Station. There are eight identical Gd-loaded liquid scintillator detectors deployed in two near (flux-weighted baseline 512 $m$ and 561 $m$) and one far (1579 $m$) underground experimental halls to detect the inverse beta decay interaction. This dissertation describes the Daya Bay Experiment and individual contributions to this experiment. Chapter 1 reviews the history of the neutrino and the neutrino oscillation phenomena. The reactor based neutrino experiments in different times are described in this chapter in detail. It presents the motivation of the Daya Bay Experiment. In Chapter 2, the neutrino detection method and the $theta_{13}$ relative measurement method are introduced. This chapter focuses on the design of the Daya Bay Experiment, including antineutrino detector, calibration system, muon veto system and muon tagging system. Chapter 3 shows the design, development, construction, and assembly of Muon Pool PMT calibration system, and presents an algorithm of calculating the muon pool PMT timing offset values. Chapter 4 focuses on the manufacture, installation and commissioning of RPC HV system. Chapter 5 presents the analyses of the radioactive isotopes induced by comic muons. The Daya Bay detector energy response model is also described in detail. The relative rate analysis results exclude a zero value from $sin^22theta_{13}$ with a significance of 7.7 standard deviation using 139 days of data, 28909 (205308) antineutrino candidates which were recorded at the far hall (near halls) and shows $sin^22theta_{13} = 0.089pm0.011$ in a three-neutrino framework. A combined analysis of the $overline nu_e$ rates and energy spectra based on the detector energy response model improved measurement of the mixing angle $sin^22theta_{13} = 0.090^{+0.008}_{-0.009}$ by using 217 days of data, 41589 (203809 and 92912) antineutrino candidates were detected in the far hall (near halls). Also the first direct measurement of the $overline nu_e$ mass-squared difference $|Delta m^2_{ee}|= (2.59^{+0.19}_{-0.20})times10^{-3}$ $eV^2$. It is consistent with $|Delta m^2_{mumu}|$ measured by muon neutrino disappearance, supporting the three-flavor oscillation model. / Ph. D.