The authors measure the time-dependent CP asymmetry parameters in B{sup 0} {yields} K{sup +}K{sup -}K{sup 0} based on a data sample of approximately 277 million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct two-body B{sup 0} decays to {phi}(1020)K{sub s}{sup 0} and {phi}(1020)K{sub L}{sup 0}. Using a time-dependent maximum-likelihood fit, they measure sin2{beta}{sub eff}({phi}K{sup 0}) = 0.48 {+-} 0.28 {+-} 0.10, and C({phi}K{sup 0}) = 0.16 {+-} 0.25 {+-} 0.09, where the first error is statistical, and the second is systematic. They also present measurements of the CP-violating asymmetries in the decay B{sup 0} {yields} f{sub 0}({yields} {pi}{sup +}{pi}{sup -})K{sub s}{sup 0}. The results are obtained from a data sample of 209 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays, also collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a time-dependent maximum-likelihood fit they measure the mixing-induced CP violation parameter S(f{sub 0}(980)K{sub S}{sup 0}) = - sin 2{beta}{sub eff}f{sub 0}(980)K{sub S}{sup 0} = -0.95{sub -0.23}{sup +0.32} {+-} 0.10 and the direct CP violation parameter C(f{sub 0}(980)K{sub S}{sup 0}) = - 0.24 {+-} 0.31 {+-} 0.15, where the first errors are statistical and …

Despite more than thirty years having elapsed since the discovery of CP violation, our understanding about the source and the nature of this phenomenon is still very limited. In the standard model of particle physics, CP violation is due to the presence of an non-irreducible weak phase in the Cabibbo-Kabayashi-Maskawa(CKM) matrix. Up to now, all the experimental results are in good agreement with the standard model. However, it is important for us to over-constrain the CKM quark-mixing matrix and explore the possibility of new physics beyond the standard model. The B meson provides an ideal place to measure CP violation due to its heavy mass and potentially large CP-violating effects. In particular, the angle {gamma} of the Unitary Triangle relating the elements of the CKM matrix is extremely crucial in terms of CP violation and constraints on the new physics models. Various methods using B{sup -} {yields} D{sup 0}K{sup -} decays have been proposed to measure based on the interference between the V{sub cb} and V{sub ub} amplitudes. Despite the simple concept, the measurement turns out to be experimentally challenging due to the small branching fraction and the small value of {tau}{sub B}, the amplitude ratio between the two contributing …

Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, integrated circuits, and wireless technologies provide the means to reach this challenging goal. This dissertation describes the development of innovative silicone-based microfabrication techniques for producing an implantable microelectrode array. The microelectrode array is a component of an epiretinal prosthesis being developed by a multi-laboratory consortium. This array will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces. Because the array is intended as a long-term implant, vital biological and physical design requirements must be met. A retinal implant poses difficult engineering challenges due to the size of the intraocular cavity and the delicate retina. Not only does it have to be biocompatible in terms of cytotoxicity and degradation, but it also has to be structurally …

This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the mu- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the mu+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be Lambda_S = 725.0 +- 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m2mu)= 7.3 +- 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.

Over the last few years, the B factories have established the Cabbibo-Kobayashi-Maskawa mechanism of CP violation in the Standard Model through the study of the decays of B mesons. The focus of Belle and BaBar has now expanded to the search for signatures of new physics beyond the Standard Model, particularly through examination of flavor-changing neutral-current transitions, which proceed through diagrams involving virtual loops. These decays are suppressed in the Standard Model, increasing sensitivity to new-physics effects but decreasing branching fractions. Exploiting large and growing datasets, BaBar and Belle have made many measurements in loop decays where a b quark transitions to an s quark, observing hints of possible deviations from Standard Model expectations in CP-violating measurements.

The Sudbury Neutrino Observatory (SNO) is a large-volume heavy water Cerenkov detector designed to resolve the solar neutrino problem. SNO observes charged-current interactions with electron neutrinos, neutral-current interactions with all active neutrinos, and elastic-scattering interactions primarily with electron neutrinos with some sensitivity to other flavors. This dissertation presents an analysis of the solar neutrino flux observed in SNO in the second phase of operation, while {approx}2 tonnes of salt (NaCl) were dissolved in the heavy water. The dataset here represents 391 live days of data. Only the events above a visible energy threshold of 5.5 MeV and inside a fiducial volume within 550 cm of the center of the detector are studied. The neutrino flux observed via the charged-current interaction is [1.71 {+-} 0.065(stat.){+-}{sub 0.068}{sup 0.065}(sys.){+-}0.02(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}, via the elastic-scattering interaction is [2.21{+-}0.22(stat.){+-}{sub 0.12}{sup 0.11}(sys.){+-}0.01(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}, and via the neutral-current interaction is [5.05{+-}0.23(stat.){+-}{sub 0.37}{sup 0.31}(sys.){+-}0.06(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}. The electron-only flux seen via the charged-current interaction is more than 7{sigma} below the total active flux seen via the neutral-current interaction, providing strong evidence that neutrinos are undergoing flavor transformation as they travel from the core of the Sun to the …

A variety of scenarios are considered which shed light upon the uses and limitations of classical geometric and topological notions in string theory. The primary focus is on situations in which D-brane or string probes of a given classical space-time see the geometry quite differently than one might naively expect. In particular, situations in which extra dimensions, non-commutative geometries as well as other non-local structures emerge are explored in detail. Further, a preliminary exploration of such issues in Lorentzian space-times with non-trivial causal structures within string theory is initiated.

Protein phosphorylation is a general mechanism for signal transduction as well as regulation of cellular function. Unlike phosphorylation in eukaryotic systems that uses Ser/Thr for the sites of modification, two-component signal transduction systems, which are prevalent in bacteria, archea, and lower eukaryotes, use an aspartate as the site of phosphorylation. Two-component systems comprise a histidine kinase and a receiver domain. The conformational change of the receiver domain upon phosphorylation leads to signal transfer to the downstream target, a process that had not been understood well at the molecular level. The transient nature of the phospho-Asp bond had made structural studies difficult. The discovery of an excellent analogue for acylphosphate, BeF{sub 3}{sup -}, enabled structural study of activated receiver domains. The structure of activated Chemotaxis protein Y (CheY) was determined both by NMR spectroscopy and X-ray crystallography. These structures revealed the molecular basis of the conformational change that is coupled to phosphorylation. Phosphorylation of the conserved Asp residue in the active site allows hydrogen bonding of the T87 O{gamma} to phospho-aspartate, which in turn leads to the rotation of Y106 into the ''in'' position (termed Y-T coupling). The structure of activated CheY complexed with the 16 N-terminal residues of FliM (N16-FliM), …

As the dimensions of semiconductor devices are scaled down, in order to achieve higher levels of integration, optical lithography will no longer be sufficient for the needs of the semiconductor industry. Alternative next-generation lithography (NGL) approaches, such as extreme ultra-violet (EUV), X-ray, electron-beam, and ion projection lithography face some challenging issues with complicated mask technology and low throughput. Among the four major alternative NGL approaches, ion beam lithography is the only one that can provide both maskless and resistless patterning. As such, it can potentially make nano-fabrication much simpler. This thesis investigates a focused ion beam system for maskless, resistless patterning that can be made practical for high-volume production. In order to achieve maskless, resistless patterning, the ion source must be able to produce a variety of ion species. The compact FIB system being developed uses a multicusp plasma ion source, which can generate ion beams of various elements, such as O{sub 2}{sup +}, BF{sub 2}{sup +}, P{sup +} etc., for surface modification and doping applications. With optimized source condition, around 85% of BF{sub 2}{sup +}, over 90% of O{sub 2}{sup +} and P{sup +} have been achieved. The brightness of the multicusp-plasma ion source is a key issue for …

The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication techniques to increase the number of electrodes and integrate electronics. After the initial designs were fabricated and tested in acute implantation, it became obvious that there was a need to characterize and understand the mechanical and electrical properties of these new structures. This knowledge would be imperative in gaining credibility for polymer microfabrication and optimizing the designs. Thin composite microfabricated devices are challenging to characterize because they are difficult to handle, and exhibit non-linear, viscoelastic, and anisotropic properties. The objective of this research is to device experiments and protocols, develop an analytical model to represent the composite behavior, design and fabricate test structures, and conduct experimental testing to determine the mechanical and electrical properties of PDMS-metal composites. Previous uniaxial stretch tests show an average of 7% strain before failure …

Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary {gamma} rays after a light-ion reaction. A primary {gamma}-ray spectrum represents the {gamma}-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary {gamma}-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary {gamma}-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei {sup 56}Fe and {sup 57}Fe. The experimental level densities in {sup 56}Fe and {sup 57}Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for {sup 56}Fe and {sup 57}Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using …

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This thesis consists of three main parts. The first one relates to boron neutron capture therapy. It summarizes the guidelines obtained by numerical simulations for the treatment of shallow and deep-seated brain tumors, as well as the results on the design of beam-shaping assemblies to moderate D-D and D-T neutrons to epithermal energies. The second part is about boron neutron capture synovectomy for the treatment of rheumatoid arthritis. Optimal neutron energy for treatment and beam-shaping assembly designs are summarized in this section. The last part is on the development of the sealed neutron generator, including experimental results on the prototype ion source and the prototype accelerator column.

After implantation of As, As + Be, and As + Ga into GaN and annealing for short durations at temperatures as high as 1500 C, the GaN films remained highly resistive. It was apparent from c-RBS studies that although implantation damage did not create an amorphous layer in the GaN film, annealing at 1500 C did not provide enough energy to completely recover the radiation damage. Disorder recovered significantly after annealing at temperatures up to 1500 C, but not completely. From SIMS analysis, oxygen contamination in the AIN capping layer causes oxygen diffusion into the GaN film above 1400 C. The sapphire substrate (A1203) also decomposed and oxygen penetrated into the backside of the GaN layer above 1400 C. To prevent donor-like oxygen impurities from the capping layer and the substrate from contaminating the GaN film and compensating acceptors, post-implantation annealing should be done at temperatures below 1500 C. Oxygen in the cap could be reduced by growing the AIN cap on the GaN layer after the GaN growth run or by depositing the AIN layer in a ultra high vacuum (UHV) system post-growth to minimize residual oxygen and water contamination. With longer annealing times at 1400 C or at …

Helium, with its two electrons and one nucleus, is a three-body system. One of the models for investigating correlated electron motion in this system is autoionization, produced via double excitation of the electrons. Predictions about the autoionization spectrum of helium have differed from each other and from preliminary experimental data. However, previous experiments have not been able to distinguish among the theoretical predictions because their energy resolution is not high enough to resolve the narrow linewidths of quasi-forbidden peaks and the resonances that appear in the highest excited states. Consequently, a team of researchers at Lawrence Berkeley National Laboratory have embarked on a project for building a high-resolution Fourier-Transform Soft X-ray (or VUV) interferometer (FTSX) to provide definitive data to answer remaining questions about the autoionization spectrum of helium. The design and construction of this interferometer is described in detail below, including the use of a flexure stage to provide the large path length difference necessary for high resolution measurements, the manufacture of x-ray beamsplitters, a description of the software, and the solution to the problems of stick-slip, vibration, and alignment. Current progress of its development is also described, as well as future goals.