Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 29 for “"polarization transfer"”.
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Polarization transfer measurements of D(e,e'p) reaction in the dip region at Q² - -0.31 GeV²/c²
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.
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Dynamic nuclear polarization of biological systems at high magnetic fields
Dynamic nuclear polarization methods were studied at high magnetic field strength and were applied to improve the sensitivity of the nuclear magnetic resonance spectroscopy of biological solids. Studies of the dynamics of electron-nuclear polarization transfer via the solid effect and thermal …
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Direct Measurements of Two Photon Exchange on Lepton-Proton Elastic Scattering Using Simultaneous Electron-Positron Beams in CLAS
… the Rosenbluth separation method and the polarization transfer technique. However, the ratio of the electric and magnetic form factors measured by those methods significantly disagree at momentum transfer <em>Q</em><sup>2</sup> > 1 GeV<sup>2</sup>. The most likely explanation of this …
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A Study of Polarized Lambda Production in Deep Inelastic Positron Scattering
… positron beam and an unpolarized target. The polarization which is transferred to these final state Lambda's depends not only on the spin composition of the Lambda baryon, but also on the effects of polarization in the hadronization process. In this thesis, the results of the polarization …
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Proton form factors in large NcQCD
… space-like data in the whole range of momentum transfer. Additionally, the ratio upGE/GM predictably is in good agreement with recent polarization transfer measurements at Jefferson Lab. The electric and magnetic radii are determined using this current world data.
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Investigation of DNP mechanisms : the solid effect
Dynamic Nuclear Polarization (DNP) enhances signal to noise in NMR experiments, by transferring the large electron Boltzmann polarization to nuclear polarization, via application of pulsed or continuous-wave microwave irradiation. This results in increases in NMR sensitivity of 2-3 orders of …
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Sensitivity-enhanced nuclear magnetic resonance of biological solids
Dynamic Nuclear Polarization (DNP) enhances the sensitivity of solid-state Nuclear Magnetic Resonance experiments via transfer of polarization from electrons to nuclei. The polarization transfer is driven by microwave irradiation near the electron Larmor frequency. Signal enhancements of up to …
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Liquid Phase Carbon-Thirteen Dynamic Nuclear Polarization Study of Monosubstituted Aromatic Compounds
… DNP experimental data were collected in a flow transfer system for different mono-substituted aromatic compounds, such as, anisole, nitrobenzene and halobenzenes. These substitute groups covered a wide range of electronic effects from strong electron donating groups to strong electron …
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A study of polarized Λ production in deep inelastic postron scattering
… reaction and then hadronizes, how much of the polarization remains in the final state particles? Many measurements are necessary to answer these questions. As a first step, A particles are generated at the HERMES experiment in Hamburg, Germany, using a polarized positron beam and an unpolarized …
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Dynamic nuclear polarization and electron spin resonance in paramagnetic solids at high field
… description of investigations of dynamic nuclear polarization (DNP) at high magnetic field as a means of improving the signal to noise in solid state NMR spectroscopy. DNP transfers the large polarization of unpaired electron spins to nuclei in a process involving sample irradiation at or near the …
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Measurement and Modeling of OPNMR Phenomena in GaAs Semiconductors
… barrier by utilizing the high electronic polarizations that can be generated through the application of polarized light.</p><p>Semiconducting materials are the fundamental building blocks of important components in most aspects of modern society, including solar cells, optical detectors, …
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Coherent Dynamic Nuclear Polarization: Mechanistic Insights and Experimental Advances
Dynamic Nuclear Polarization (DNP) enhances the sensitivity of solid-state Nuclear Magnetic Resonance (NMR) by transferring polarization from electrons to nuclei. While traditional continuous-wave (CW) DNP has advanced through improved radical design, the development of pulsed DNP—employing short, …
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Beyond the Born Approximation: A Precise Comparison of e+p and e-p Elastic Scattering in the CEBAF Large Acceptance Spectrometer (CLAS)
… of the proton measured by the Rosenbluth and the polarization transfer methods differ by a factor of 3 at four momentum transfer squared (<em>Q</em>²)=5.6 GeV². The two photon exchange (TPE) effect is the leading candidate to explain this discrepancy. The theoretical estimates of the TPE effect …
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Development of Magnetic Resonance Spectroscopic Imaging Methods to Assess Tumour Metabolism
… of these nuclei. Sensitivity can be increased by transferring the hyperpolarization to spin coupled protons provided that there is not significant polarization loss during the transfer. To exploit both the slow relaxation offered by storing the hyperpolarization in the low gamma nucleus and the …
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Measurements of Compton Scattering on the Proton at 2--6 GeV
… scattering on the proton at high momentum transfers (and high p⊥) can be an effective method to study its short-distance structure. An experiment has been carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton for 2.3-5.7 GeV electron beam energies and a …
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Measurements of Compton scattering on the proton at 2-6 GeV
… Scattering on the proton at high momentum transfers(and high p⊥) can be an effective method to study its short-distance structure. An experiment has been carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton for 2.3-5.7 GeV electron beam energies and a …
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High Field DNP NMR probe design and application in crystalline solids
Dynamic nuclear polarization (DNP) is a valuable tool which can be used to enhance nuclear magnetic resonance (NMR) signal intensities in a variety of biological and materials science systems, by transferring polarization from unpaired electrons to nuclei. In this thesis, the mechanical design and …
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Solid-state NMR investigation of viral fusion glycoprotein 41 (gp41)
… [beta]-sheet character. Water and lipid ¹H polarization transfer to the protein revealed that the TMD is well inserted into the membrane, while the FPPR and MPER are more hydrated and exposed to the membrane surface. Importantly, we observed correlation signals between the FP-FPPR and the …
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SPECTROSCOPIC STUDIES OF NUCLEAR SPINS POLARIZED VIA SPIN EXCHANGE OPTICAL PUMPING AND DYNAMIC COUPLING IN CRYPTOPHANE HOST-GUEST COMPLEXES
… from extremely small (Boltzmann) nuclear spin polarization at thermal equilibrium--in even the strongest of magnets. This dissertation focuses on selected research areas that maybe used to combat the limitations presented by NMR and measure weak spectral responses with atomic-scale precision. …
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