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Full-Text Articles in Physics

A Search For Wimp Dark Matter Using An Optimized Chi-Square Technique On The Final Data From The Cryogenic Dark Matter Search Experiment (Cdms Ii)., Manungu Joseph Kiveni Dec 2012

A Search For Wimp Dark Matter Using An Optimized Chi-Square Technique On The Final Data From The Cryogenic Dark Matter Search Experiment (Cdms Ii)., Manungu Joseph Kiveni

Physics - Dissertations

During the last two decades, cosmology has become a precision observational science thanks (in part) to the incredible number of experiments performed to better understand the composition of the universe. The large amount of data accumulated strongly indicates that the bulk of the universe’s matter is in the form of nonbaryonic matter that does not interact electromagnetically. Combined evidence from the dynamics of galaxies and galaxy clusters confirms that most of the mass in the universe is not composed of any known form of matter. Measurements of the cosmic microwave background, big bang nucleosynthesis and many other experiments indicate ...


Linear Sigma Models In Qcd And S3 Symmetry For Neutrinos, Muhammad Naeem Shahid Aug 2012

Linear Sigma Models In Qcd And S3 Symmetry For Neutrinos, Muhammad Naeem Shahid

Physics - Dissertations

This thesis has two parts with different topics in particle physics. In part I, we consider various linear sigma models and their applications to scalar mesons. It is shown that the tree amplitude for ππ scattering in the minimal linear sigma model has an exact expression which induces an infinite geometric series in which the pattern for both the I = 0 and I = 2 s-wave scattering lengths to orders $p^2$, $p^4$ and $p^6$ seems to agree with chiral perturbation theory predictions. The model is then gauged to study the mass differences between the vector meson and the ...


Microstrip Superconducting Quantum Interference Devices For Quantum Information Science, Michael Paul Defeo Aug 2012

Microstrip Superconducting Quantum Interference Devices For Quantum Information Science, Michael Paul Defeo

Physics - Dissertations

Quantum-limited amplification in the microwave frequency range is of both practical and fundamental importance. The weak signals corresponding to single microwave photons require substantial amplification to resolve. When probing quantum excitations of the electromagnetic field, the substantial noise produced by standard amplifiers dominates the signal, therefore, several averages must be accumulated to achieve even a modest signal-to-noise ratio. Even worse, the back-action on the system due to amplifier noise can hasten the decay of the quantum state. In recent years, low-noise microwave-frequency amplification has been advancing rapidly and one field that would benefit greatly from this is circuit quantum electrodynamics ...


Development Of Spect And Ct Tomographic Image Reconstruction, Levon Orion Vogelsang Jun 2012

Development Of Spect And Ct Tomographic Image Reconstruction, Levon Orion Vogelsang

Physics - Dissertations

The purpose of this study was to contribute to the advancement of statistically-based iterative reconstruction algorithms and protocols for both SPECT and micro CT data. Major contributions of this work to SPECT reconstruction include formulation and implementation of fully three-dimensional voxel-based system matrix in parallel-beam, fan-beam, and cone-beam collimator geometries while modeling the process of attenuation, system resolution and sensitivity. This is achieved by casting rays through a volume of voxels and using ray-voxel intersection lengths to determine approximate volume contributions. Qualitative and quantitative analysis of reconstructed Monte Carlo data sets show that this is a very effective and efficient ...


Effective Field Theories In Cosmology, Riccardo Penco Jun 2012

Effective Field Theories In Cosmology, Riccardo Penco

Physics - Dissertations

During the last 20 years, a large amount of detailed cosmological observations have promoted cosmology to the rank of high-precision science. Remarkably, all the observations currently available can be accounted for by assuming that (i) the universe is approximately homogeneous and isotropic on large scales, (ii) gravitational interactions are described by General Relativity with a non-vanishing cosmological constant and (ii) 85% of the matter content of the universe is in the form of dark matter, a presently unknown type of matter which interacts with ordinary matter only gravitationally. Current theoretical efforts are focused on gaining a deeper understanding of the ...


Measurement Of Neutron Radius In Lead By Parity Violating Scattering Flash Adc Daq, Ahmed Zafar Jun 2012

Measurement Of Neutron Radius In Lead By Parity Violating Scattering Flash Adc Daq, Ahmed Zafar

Physics - Dissertations

This dissertation reports the experiment PREx, a parity violation experiment which is designed to measure the neutron radius in 208Pb. PREx is performed in hall A of Thomas Jefferson National Accelerator Facility from March 19th to June 21st. Longitudionally polarized electrons at energy 1 GeV scattered at and agnle of θlab = 5.8° from the Lead target. Beam corrected pairty violaing counting rate asymmetry is (Acorr = 594 ± 50(stat) ± 9(syst))ppb at Q2 = 0.009068GeV2.

This dissertation also presents the details of Flash ADC Data Acquisition(FADC DAQ) system for Moller polarimetry in ...


Geometries In Soft Matter, Zhenwei Yao May 2012

Geometries In Soft Matter, Zhenwei Yao

Physics - Dissertations

No abstract provided.


Physics On Noncommutative Spacetimes, Pramod Padmanabhan May 2012

Physics On Noncommutative Spacetimes, Pramod Padmanabhan

Physics - Dissertations

The structure of spacetime at the Planck scale remains a mystery to this date with a lot of insightful attempts to unravel this puzzle. One such attempt is the proposition of a `pointless' structure for spacetime at this scale. This is done by studying the geometry of the spacetime through a noncommutative algebra of functions defined on it. We call such spacetimes 'noncommutative spacetimes'. This dissertation probes physics on several such spacetimes. These include compact noncommutative spaces called fuzzy spaces and noncompact spacetimes. The compact examples we look at are the fuzzy sphere and the fuzzy Higg's manifold. The ...


Electron Drift-Mobility Measurements In Polycrystalline Cuin1-Xgaxse2 Solar Cells, Steluta A. Dinca, Eric A. Schiff, William N. Shafarman, Brian Egaas, Rommel Noufi, David L. Young Mar 2012

Electron Drift-Mobility Measurements In Polycrystalline Cuin1-Xgaxse2 Solar Cells, Steluta A. Dinca, Eric A. Schiff, William N. Shafarman, Brian Egaas, Rommel Noufi, David L. Young

Physics

We report photocarrier time-of-flight measurements of electron drift mobilities for the p-type CuIn1-xGaxSe2 films incorporated in solar cells. The electron mobilities range from 0.02 to 0.05 cm^2/Vs and are weakly temperature-dependent from 100–300 K. These values are lower than the range of electron Hall mobilities (2-1100 cm2/Vs) reported for n-type polycrystalline thin films and single crystals. We propose that the electron drift mobilities are properties of disorder-induced mobility edges and discuss how this disorder could increase cell efficiencies.