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Full-Text Articles in Physics
Studies Of Pentaquarks And Of Noncommutative Field Theory, Vahagn Nazaryan
Studies Of Pentaquarks And Of Noncommutative Field Theory, Vahagn Nazaryan
Dissertations, Theses, and Masters Projects
Several experiments reported seeing evidence in their data of a new particle, the strangeness +1 Theta+ pentaquark made of four quarks and an antiquark. In the first few chapters of this dissertation we study four-quark-antiquark systems within the framework of a constituent quark model. We describe the Theta+ as a member of a spin-½ pentaquark antidecuplet. For both parity-odd, and parity-even antidecuplets we derive useful decompositions of the quark model wave functions that allow for easy computation of color-flavor-spin-orbital matrix elements, and we compute mass splittings within the antidecuplet. We study parity-even antidecuplet in an effective theory with dominant flavor-spin …
Solid State Nmr Characterization Of Conductive Polyanilines, Yanina Anatolievna Goddard
Solid State Nmr Characterization Of Conductive Polyanilines, Yanina Anatolievna Goddard
Dissertations, Theses, and Masters Projects
Different forms of ring deuterated polyaniline with different conductivity have been characterized by solid state deuteron nuclear magnetic resonance.;Quadrupole echo (QE) spectra of all forms of polyaniline consist of a superposition of lineshapes for nearly rigid aromatic rings and a small fraction of rings which undergo fast 180?? flips. The intensity of the fast flipping component is temperature dependent and different for conductive emeraldine salt (ES) and non-conductive emeraldine base (EB). This is a manifestation of the different structure and morphology of these polymers.;Simultaneous measurements of QE lineshapes and the relaxation time anisotropies allowed an accurate description of motion in …
Measurement Of The Branching Fraction For Neutral Kaon(Long) Decaying To Muon-Electron-Positron, Andrew J. Norman
Measurement Of The Branching Fraction For Neutral Kaon(Long) Decaying To Muon-Electron-Positron, Andrew J. Norman
Dissertations, Theses, and Masters Projects
This dissertation describes the measurement of the decay of the long lived neutral kaon into two muons and two electrons. The measurement was performed using the data taken during experiment E871 which was performed on the B5 beamline at the Alternating Gradient Synchrotron (AGS) of the Brookhaven National Laboratory (BNL). The branching ratio B( K0L → mu+mu-e +e-) is sensitive to the absorptive portion of the long distance amplitude for decays of the form K0L → ℓ+ℓ- and can be used to properly extract the short distance weak interaction amplitudes from the dileptonic events.;Measurement of K0L → mu+mu-e +e- additionally …
Characterization Of Transient Behaviors In A Colliding Pulse Mode-Locked (Cpm) Laser, Wei Yang
Characterization Of Transient Behaviors In A Colliding Pulse Mode-Locked (Cpm) Laser, Wei Yang
Dissertations, Theses, and Masters Projects
A colliding pulse mode-locked (CPM) laser achieves sub-picosecond operation by synchronizing two counter-propagating pulse trains to form a standing wave in a thin absorber jet. When properly aligned, these lasers maintain mode-locking for more than 100 seconds (1010 pulses), but eventually cease mode-locking for short periods of time. This thesis examines the characteristics of these transient events, when CPM mode-locking ceases (dropout) and when it resumes (dropin). The dropout is an apparently rapid event, typically lasting no longer than 5 microseconds or less than 500 pulses. The dropin takes significantly longer time, often has structure, and has a clear power …
Dual Energy Scanning Beam X -Radiography, Randolph Frank Wojcik
Dual Energy Scanning Beam X -Radiography, Randolph Frank Wojcik
Dissertations, Theses, and Masters Projects
Dual energy X-radiography is a method first developed in the mid-1970's by which one uses the information contained in the energy spectrum of the transmitted X-ray flux through an object. With this information one can distinguish the types of materials present in a radiograph and thus allow a computer to subtract them from the image enhancing the contrast of the remaining materials. Using this method, one can see details, which would have been hidden by overlying structures of other materials such as seen in radiographs of parts, made up of mixtures of metals and composites. There is also great interest …
Spontaneous Pulse Formation In Bistable Systems, George A. Andrews
Spontaneous Pulse Formation In Bistable Systems, George A. Andrews
Dissertations, Theses, and Masters Projects
This thesis considers localized spontaneous pulse formation in nonlinear, dissipative systems that are far from equilibrium and which exhibit bistability. It is shown that such pulses can form in systems that are dominated by the combined effects of: (1) a saturable amplifying or gain region, (2) a saturable absorbing or loss region, and (3) cavity effects. Analysis is based upon novel models for both an inertialess material in which the absorber responds instantaneously and inertial material in which there is temporal delay in the response. Additionally, we include the situation where the material does not fully relax between pulses, i.e. …
Control Of Integrable Hamiltonian Systems And Degenerate Bifurcations, Christopher W. Kulp
Control Of Integrable Hamiltonian Systems And Degenerate Bifurcations, Christopher W. Kulp
Dissertations, Theses, and Masters Projects
In this dissertation, we study the control of near-integrable systems. A near-integrable system is one whose phase space has a similar structure to an integrable system during short time periods and for some parameter regime. We begin by studying the control of integrable Hamiltonian systems. The controller targets an exact solution to the integrable system using dissipative and conservative terms. We find that a Takens-Bogdanov bifurcation occurs in the limit of no dissipative control. The presence of a Takens-Bogdanov bifurcation implies that the control is highly susceptible to noise. We illustrate our results using a two- and four-dimensional integrable systems …
Ultraviolet Sources For Advanced Applications In The Vacuum Uv And Near Uv, Sheng Peng
Ultraviolet Sources For Advanced Applications In The Vacuum Uv And Near Uv, Sheng Peng
Dissertations, Theses, and Masters Projects
This dissertation documents a systematic study consisting of experimental investigations and theoretical analyses of intense ultraviolet sources in VUV and near-UV. Some engineering issues regarding two prototypes of electrodeless lamps using rf and microwave are discussed.;Various excimers that produce intense UV light are investigated, including: (1) A benchmark Xe2 excimer which has been proven to be very efficient in our novel rf capacitively coupled discharge lamp; (2) A rarely studied excimer, KrI, which suffers from predissociation and was reported to be very weak or invisible by most of other studies; (3) XeI excimer whose emission dominates around 253 nm and …