Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 201-212).

Not available / text

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xix, 302 p. : ill. (some col.). Advisor: David H. Weinberg, Department of Astronomy. Includes bibliographical references (p. 291-302).

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiv, 86 p.; also includes graphics. Includes bibliographical references (p. 83-86).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xviii, 319 p.; also includes graphics. Includes bibliographical references (p. 310-319). Available online via OhioLINK's ETD Center

The dark matter search CRESST-II completed its most recent run, Run 32, in 2011. Compared to previous runs, the quantity of data taken in this run increased , significantly. In this work, Oxrop, analysis software in use within the CRESST collaboration, is upgraded to analyse this new data. At the same time, Oxrop's internal structure is improved so that it can now handle data from detectors across different experiments consistently. This upgrade was performed with a view to developing Oxrop's candidacy for use with EURECA, a future dark matter experiment. Oxrop is then used to model CRESST-II data .. First, light detector response to scintillation light produced in y interactions in CRESST -Il' s target crystals is examined. A factor influencing detector efficiency is the time constant of scintillation light production, and this light detector examination is performed with a view to extracting the scintillation time constants of the target crystals. A simple model of light detector response of one exponential rise and two exponential decay times is initially considered. It is shown that this simple model does not closely match the light detector response to y interactions in the crystal scintillator. Empirical extensions to this expected model are then made, allowing for additional decay times. These extensions allow the light detector response to crystal scintillator interactions to be well modelled, and allow estimates of the millikelvin y scintillation time of Ca W04 and Zn W04. This model is then also applied to X-ray interactions directly in the light detectors. It is seen that, even with these model extensions, interactions directly in the light detector still show significant tension with the applied model. This implies that direct calibration of light detectors with X-rays is not possible without a further understanding of light detector response, or that future direct calibrations should be done with optical photons. Position dependent effects in Run 32 calibration data are then studied. A phenomenon that has previously been considered as unrelated to position dependence, the anti-correlation effect between phonon and light detector signals, is shown to exhibit a position dependent effect in at least one lightjphonon detector pair under study. Additionally, the collection efficiency of the light detector is shown to be related to the mean interaction position. Collection efficiency is found to reduce when mean interaction position is close to the cylindrical surfaces of CRESST's Ca W04 target crystals. The magnitude of the difference in light collection: efficiency between surface and bulk interactions is also seen to be correlated with high energy light detector resolution. The WIMP-nucleon cross section limits resulting from the CRESST-II commissioning run (2007) are also reanalysed in this work. The original analysis of the commissioning run accounted only for tungsten recoils in the Ca W04 crystals used in CRESST - II. Here, interactions from calcium and oxygen nuclei are also accounted for. The resulting WIMP-nucleon cross section limits were improved at light WIMP masses -0(10 GeV j c2). These limits show a mild tension with a recent dark matter analysis of Run 32, particularly for WIMP masses below 10 GeV j c2. Possible causes of this tension are discussed

A thesis submitted in ful lment of the requirements for the degree of Doctor of Philosophy in the School of Physics July 2017. / Based on the Marenostrum-MultiDark Simulation of galaxy Clusters (MUSIC) we develop semi-analytical models which provide multi-wavelength emission maps generated by dark matter (DM) annihilation processes in galaxy clusters and their sub-halos. We focus on radio and gamma-ray emission maps from neutralino DM annihilation processes testing two different neutralino masses, Mx = 35 GeV and 60 GeV along with two different models of the magnetic elds. A comparison of the radio ux densities from our DM annihilation model with the observed difuse radio emission from the Coma cluster shows that they are of the same order of magnitude. We determine the DM densities with a Smoothed Particle Hydrodynamics (SPH) kernel. This enables us to integrate the DM annihilation signal along any given line-of-sight through the volume of the cluster. In particular it allows us to investigate the contribution of sub-halos to the DM annihilation signal with very high resolution. Zooming in on a subset of high mass-to-light ratio (M/L) DM sub-halos, i.e. DM sub-halos with very low baryon content, we demonstrate that such targets can generate prominent annihilation signals. The radial distribution of high M/L DM sub-halos is more strongly peaked at R200crit = 1 compared to the distribution of all sub-halos which may suggest that the search for DM annihilation signals from sub-halos in clusters is most promising at R200crit. The radio ux densities from DM sub-halos are well within the sensitivity limit of the Square Kilometer Array (SKA) with an integration time of 1000 hours, and unlike clusters their gamma-ray spectrum is seen to be dominated by pion decay over a wide range of gamma-ray energies. Our model makes clear predictions for future radio and gamma-ray observations of the DM annihilation signals in clusters and their sub-halos. / LG2018

A thesis submitted to the Department of Physics, University of the Witwatersrand in fulfilment of the academic requirements of the degree of Doctor of Philosophy. Johannesburg, June 17, 2016. / The nature of dark matter remains one of the most significant problems in modern physics. One candidate hypothesis with strong theoretical motivation is a WIMP (Weakly Interacting Massive Particle) in the form of the supersymmetric neutralino. Although this lacks experimental evidence, supersymmetry may manifest in collider experiments and also has observable consequences in the emission of annihilation products from cosmic structures which would play host to large neutralino densities. Historically, interest has been focussed upon the direct detection of WIMPs, as well as indirect observation through -rays produced by pair-annihilation processes. In this work we present a detailed argument for a multi-frequency observational strategy. We motivate this by studying the redshift evolution of radio synchrotron radiation emitted by WIMP annihilation-product electrons. In so doing, we demonstrate the potential power of the SKA to probe the neutralino parameter space, being able to produce constraints several orders of magnitude better than current limits and distinguish between differing neutralino masses and annihilation channels. Furthermore, we motivate the SKA as a machine to study dark matter by discussing its ability to characterise cosmic magnetic fields through rotation measures and polarimetry, as well as resolve between non-thermal emissions produced by dark matter and those resulting from strictly baryonic processes, like star formation. These technical capabilities obviate the central uncertainties in the study of synchrotron radiation. Additionally, we highlight optimal laboratories for neutralino detection via the SKA, based on structures that might produce dark matter emissions with lower background synchrotron radiation. In particular we highlight galaxies and galaxy clusters at redshifts z 1 and local dwarf spheroidal galaxies. Finally, we demonstrate the potential of X-rays, through the ASTRO-H mission, to compliment the SKA in a multi-frequency search. We then demonstrate our multi-frequency approach in the analysis of several prominent claims of signals compatible with dark matter-induced emissions. Showing that models designed to account for the AMS-2/Fermi/PAMELA antiparticle and galactic centre -ray excesses are incompatible with existing data as well as demonstrating that a dark matter interpretation of the Reticulum-2 -ray excess is untenable for a wide range of dark matter particle masses. / LG2017

An ever-growing body of evidence suggests that dark matter exists and is abundant in our universe. Although the direct detection of dark matter has yet to be realized, the intensity of the experimental and theoretical search continues to amplify. The question is no longer whether dark matter exists, but rather what is its fundamental nature and how can it be known. Many large-scale, international experiments are actively searching for one class of dark matter candidates, weakly interacting massive particles (WIMPs). While indirect searches, such as those looking for the creation of dark matter in particle accelerators or for the Standard Model byproducts of dark matter annihilation, are contributing significantly to our understanding of the properties WIMPs may have, direct searches, such as those using cryogenic liquids and solids to look for scattering, have produced the most stringent limits on the properties of WIMPs. Liquid xenon (LXe) detectors continue to lead the field in the search for the direct detection of WIMPs. The success of experiments using LXe relies upon decades of measurements of the fundamental properties of LXe itself, as well as thorough characterization of the detectors that utilize this amazing element. One frontier of LXe detectors is at low energies. Next-generation LXe detectors, such as XENON1T, require a better understanding of the response of LXe to particle interactions as a function of electric field, as well as more precise measurements of the radioactive backgrounds that contribute to low-energy electronic recoil interactions. In this thesis, I describe details of efforts to characterize the stability of the XENON100 detector during its primary dark matter search periods in 2010-2012. I examine the electronic recoil data for any indications of periodic behavior, and compare the XENON100 result with a dark matter annual modulation claim by DAMA/LIBRA. I also describe the design, construction, and performance of a dedicated experiment to measure the low-energy properties of LXe, in particular the energy and electric field dependence of the response of LXe to electronic recoils. Finally, I describe the design and performance of an atom trap trace analysis device for assaying the levels of radioactive krypton in LXe dark matter detectors.

Yeung, Shek = 暗能量和暗物質模型課題 / 楊碩. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 88-91). / Abstracts in English and Chinese. / Yeung, Shek = An neng liang he an wu zhi mo xing ke ti / Yang Shuo. / Chapter 1 --- Overview of Cosmology --- p.1 / Chapter 1.1 --- The Friedmann-Robertson-Walker Metric and the Friedmann Equations --- p.1 / Chapter 1.2 --- The Hubble constant and the Expansion of the Universe --- p.3 / Chapter 1.3 --- The Energy Contents in the Universe --- p.4 / Chapter 1.4 --- Cosmological Observations --- p.8 / Chapter 2 --- Review of CMB Physics --- p.13 / Chapter 2.1 --- The Anisotropy Spectrum --- p.13 / Chapter 2.2 --- The Boltzmann Equations and Einstein Field Equation --- p.15 / Chapter 2.3 --- Initial Conditions --- p.18 / Chapter 2.4 --- Inhomogeneities of Matters --- p.21 / Chapter 2.5 --- Inhomogeneities and Anisotropies of Photons --- p.23 / Chapter 2.5.1 --- Tightly Coupled Limit of the Boltzmann equations --- p.23 / Chapter 2.5.2 --- Diffusion Damping --- p.25 / Chapter 2.5.3 --- Free Streaming --- p.25 / Chapter 2.5.4 --- Cosmological Parameters --- p.26 / Chapter 3 --- Extra Dimension Model with Casimir Effect --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Extra Dimension Model --- p.29 / Chapter 3.3 --- The Casimir Effect --- p.34 / Chapter 3.4 --- Results and Conclusion --- p.40 / Chapter 4 --- Decaying Sterile Neutrino Model --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- The Model --- p.46 / Chapter 4.3 --- Results and Conclusion --- p.61 / Chapter 5 --- Summary of the Thesis --- p.86 / Bibliography --- p.88