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Full-Text Articles in Physics
The Search For Dark Matter Annihilation In Galaxy Clusters At Veritas, James V. Tucci
The Search For Dark Matter Annihilation In Galaxy Clusters At Veritas, James V. Tucci
Open Access Dissertations
Recent data and cosmological models point to a significant fraction of the Universe being comprised of Cold Dark Matter (DM), though little is known about it directly as it does not interact electromagnetically. The most likely explanation for DM is a Weakly Interacting Massive Particle (WIMP) having a mass as low as ∼10 GeV to as high as ∼10 TeV. WIMPs are believed to be their own antiparticles and self-annihilate into a variety of lighter particles including γ-rays. Many direct detection, indirect detection, and direct production schemes have been proposed to search for the elusive WIMP. Galaxy clusters, consisting of …
Elastic Waves Along A Fracture Intersection, Bradley C. Abell
Elastic Waves Along A Fracture Intersection, Bradley C. Abell
Open Access Dissertations
Fractures and fracture networks play a significant role in the subsurface hydraulic connectivity within the Earth. While a significant amount of research has been performed on the seismic response of single fractures and sets of fractures, few studies have examined the effect of fracture intersections on elastic wave propagation. Intersections play a key role in the connectivity of a fracture network that ultimately affects the hydraulic integrity of a rock mass. In this dissertation two new types of coupled waves are examined that propagate along intersections. 1) A coupled wedge wave that propagates along a surface fracture with particle motion …
Transport Studies Of Reentrant Integer Quantum Hall States Forming In The Two-Dimensional Electron Gas, Nianpei Deng
Transport Studies Of Reentrant Integer Quantum Hall States Forming In The Two-Dimensional Electron Gas, Nianpei Deng
Open Access Dissertations
The two dimensional electron gas subjected to a magnetic field has been a model system in contemporary condensed matter physics which generated many beautiful experiments as well as novel fundamental concepts. These novel concepts are of broad interests and have benefited other fields of research. For example, the observations of conventional odd-denominator fractional quantum Hall states have enriched many-body physics with important concepts such as fractional statistics and composite fermions. The subsequent discovery of the enigmatic even-denominator ν=5/2 fractional quantum Hall state has led to more interesting concepts such as non-Abelian statistics and pairing of composite fermions which can be …
Efficient And Coherent Frequency Conversions And Nonlinear Interference In Optical Parametric And Atomic Raman Processes, Yu Ding
Open Access Dissertations
By implementing a parametric down-conversion process with a strong signal field injection, we demonstrate that frequency down-conversion from pump photons to idler photons can be a coherent process. Contrary to a common misconception, we show that the process can be free of quantum noise. With an interference experiment, we demonstrate that coherence is preserved in the conversion process. This technique could lead to a high-fidelity quantum state transfer from a high-frequency photon to a low-frequency photon and connect a missing link in quantum networks. ^ Coherent and efficient nonlinear interaction and frequency conversion are of great interest in many areas …
Beam-Induced Radiation Heating On The Superconducting Undulator At The Advanced Photon Source, Laura Elizabeth Boon
Beam-Induced Radiation Heating On The Superconducting Undulator At The Advanced Photon Source, Laura Elizabeth Boon
Open Access Dissertations
In January 2013 the Advanced Photon Source (APS), a 7 GeV synchrotron X-ray source, commissioned a Superconducting Undulator (SCU). The superconducting magnet is thermally isolated from the beam vacuum chamber, which absorbs the beam-induced heating. Previous beam induced heat load studies at other laboratories had not included a robust calculation of radiation heating from the upstream dipole magnet. The mitigation of the radiation heating mechanism, and production of photoelectrons to seed an electron cloud was studied for this thesis. ^ An analytical model was developed to predict the radiation heat load on the SCU chamber. This model was benchmarked with …
Gamma-Ray Observations Of X-Ray Binaries, Angelo Varlotta
Gamma-Ray Observations Of X-Ray Binaries, Angelo Varlotta
Open Access Dissertations
The detection of GeV/TeV emission from X-ray binaries (XRBs) has established a new class of high-energy (HE, >0.1 GeV) and very-high-energy (VHE, >100 GeV) gamma-ray emitters. XRBs are formed by a compact object, either a neutron star or a black hole, and by an optical companion star. Some XRBs are known to possess collimated relativistic jets, and are called microquasars. VERITAS has conducted observations of the high-mass X-ray binary (HMXB) 1A 0535+262 and of the microquasar Cygnus X-3. Many theoretical models predict VHE emission when these sources manifest persistent relativistic jets or transient ejections. In light of these considerations, VERITAS …