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Full-Text Articles in Physical Sciences and Mathematics
Measurement Of Electroweak Asymmetries In Vector Electron Positron Scattering At 0.1 Less Than Q(2) Less Than 0.4 (Gev/C)(2), Jeffery A. Secrest
Measurement Of Electroweak Asymmetries In Vector Electron Positron Scattering At 0.1 Less Than Q(2) Less Than 0.4 (Gev/C)(2), Jeffery A. Secrest
Dissertations, Theses, and Masters Projects
This work is based on the first engineering run of the G 0 experiment from October 2002 though January 2003 in Hall C at Jefferson Lab. The G0 experiment will be the first to measure the weak neutral form factors: GEZ( Q2), GMZ( Q2) and GAe( Q2) and to extract the proton's strange form factors: GEs(Q2) and GMs(Q 2) via a Rosenbluth separation over a range of Q 2 (0.1--1.0 (GeV/c)2). This will require four sets of measurements: forward angle measurements with a proton target, and three sets of backward angle measurements with a hydrogen and deuterium target. The measurements …
Automated Peak Identification For Time -Of -Flight Mass Spectroscopy, Haijian Chen
Automated Peak Identification For Time -Of -Flight Mass Spectroscopy, Haijian Chen
Dissertations, Theses, and Masters Projects
The high throughput capabilities of protein mass fingerprints measurements have made mass spectrometry one of the standard tools for proteomic research, such as biomarker discovery. However, the analysis of large raw data sets produced by the time-of-flight (TOF) spectrometers creates a bottleneck in the discovery process. One specific challenge is the preprocessing and identification of mass peaks corresponding to important biological molecules. The accuracy of mass assignment is another limitation when comparing mass fingerprints with databases.;We have developed an automated peak picking algorithm based on a maximum likelihood approach that effectively and efficiently detects peaks in a time-of-flight secondary ion …
Studies In Cpt Violation And 331 Models, David L. Anderson
Studies In Cpt Violation And 331 Models, David L. Anderson
Dissertations, Theses, and Masters Projects
The Standard Model of particles and fields has been around for about 30 years, and has been remarkably successful. However, it is widely believed to be incomplete, and theorists have studied various extensions to the model. These extensions can take many forms. An example of this is the framework Colladay and Kostelecky have proposed for studying Lorentz and CPT violation in a natural extension of the Standard Model. We determined the first bounds on the parameters in the Higgs sector. The bounds on the CPT---even asymmetric coefficients arise from the one-loop contributions to the photon propagator, those from the CPT---even …
Optical Characterization Of Ferromagnetic Heterostructure *Interfaces And Thin Films, Haibin Zhao
Optical Characterization Of Ferromagnetic Heterostructure *Interfaces And Thin Films, Haibin Zhao
Dissertations, Theses, and Masters Projects
This thesis presents optical characterizations of interfaces in ferromagnetic heterostructures and thin films used for spin polarized electronic devices. In these experiments, femtosecond laser spectroscopies are exploited to investigate the interface magnetization reversal, spin precession, and band offset, which are crucial in determining the performances of spintronic devices.;First, magnetization-induced second-harmonic-generation (MSHG) is applied to study interface magnetism in a hybrid structure containing a noncentrosymmetric semiconductor---Fe/AlGaAs. The reversal process of Fe interface layer magnetization is compared with the bulk magnetization reversal. In Fe/AlGaAs (001), the interface magnetization is found to be decoupled from the bulk magnetization based on the different switching …
Static And Ultrafast Moke Studies Of Exchange -Biased Cobalt Systems, Keoki A. Seu
Static And Ultrafast Moke Studies Of Exchange -Biased Cobalt Systems, Keoki A. Seu
Dissertations, Theses, and Masters Projects
We have studied the exchange bias interaction in metal bilayers IrMn/Co and FeMn/Co using the static and ultrafast pump-probe Kerr effects. Experiments conducted on wedged Co samples show that the exchange bias interaction is sensitive to the buffer layers grown beneath it when the antiferromagnetic layer is FeMn. The exchange bias strength, as measured by the shift in the magnetic hysteresis loop, follows a 1/tFM dependence as reported in the literature. The time-domain pump-probe experiments reveal coherent magnetization oscillations, whose frequencies are comparable to those measured by frequency-domain FMR measurements, and they fit well to FMR equations for the frequency. …
Time-Resolved Magneto-Optical Imaging Of Superconducting Ybco Thin Films In The High-Frequency Ac Current Regime, Alexander Frey
Time-Resolved Magneto-Optical Imaging Of Superconducting Ybco Thin Films In The High-Frequency Ac Current Regime, Alexander Frey
Dissertations, Theses, and Masters Projects
No abstract provided.
Ultrafast Laser Spectroscopy Of Half -Metallic Chromium Dioxide, Hailong Huang
Ultrafast Laser Spectroscopy Of Half -Metallic Chromium Dioxide, Hailong Huang
Dissertations, Theses, and Masters Projects
This thesis presents ultrafast laser pump-probe differential transmission experiments on epitaxial CrO2 (110). The experiments were conducted at the wavelengths of 600 nm, 800 nm and 1200 nm, corresponding to the transition energies of 2 eV, 1.5 eV and 1 eV respectively. The wavelength dependent results, comparing with linear optical absorption, revealed the electronic structure of the material. The experimental results also showed polarization dependence of the probe beams. This is attributed to the electronic orbital anisotropy.;Temperature dependence was observed in the pump-probe experiments. The ultrafast transmission data show similar temperature dependence as ultrafast MOKE (Magneto-Optical Kerr Effect) data. A …
Spectroscopy, Production And Decays Of Pentaquarks, Herry Kwee
Spectroscopy, Production And Decays Of Pentaquarks, Herry Kwee
Dissertations, Theses, and Masters Projects
An extensive study of the production, decay and spectroscopy of pentaquarks has been done in this dissertation. at the time of this writing, the existence of the pentaquark has not been conclusively established. New experimental results for the pentaquark will come in the months ahead. A brief review of the current experimental status of the pentaquark is given in the Introduction. The pentaquark states are analyzed using the constituent quark model with the lowest-lying pentaquark multiplet shown to be an antidecuplet. The mass splittings within the antidecuplet emerge from spin-color and spin-flavor interactions between constituents and from hidden strangeness in …
Carbon Nanosheets And Carbon Nanotubes By Rf Pecvd, Mingyao Zhu
Carbon Nanosheets And Carbon Nanotubes By Rf Pecvd, Mingyao Zhu
Dissertations, Theses, and Masters Projects
A planar antenna RF plasma enhanced chemical vapor deposition apparatus was built for carbon nanostructure syntheses. When operated in inductive and capacitive plasma discharging modes, two carbon nanostructures, carbon nanotube (CNT) and carbon nanosheet (CNS), were synthesized, respectively.;A nanosphere lithography method was developed and used to prepare catalyst patterns for CNT growth. Using capacitively coupled C2H2/NH 3 plasma, randomly oriented CNT were synthesized on Ni dot patterned Si substrates. Aligned CNT arrays were grown on SiO2 coated Si substrates, using both C2H2/NH3 and CH 4/H2 capacitive plasmas.;When operated in inductive coupling mode, CNS were successfully deposited on a variety of …
Internal Magnetic Field Distribution Of A Type Ii High Tc Superconductor With Non-Conducting Inclusions, Yuxin Dai
Dissertations, Theses, and Masters Projects
The internal magnetic field distributions for a type II superconductor (a single crystal YBa2Cu3O7-delta ) with large normal inclusions (YBa2Cu3O 7-delta) are studied. A model based on the London Equations has been successfully developed and applied to the interpretation of the pSR data on this system. In our model, these inclusions are assumed to be cylindrical in shape and infinite in length. Therefore, this model should be especially appropriate for the prediction of field distributions in single crystal superconductors in which columnar defects have been purposely introduced to enhance pinning.;muSR experiments on a large single-crystal sample of YBa2C u3O7-delta with …