Hygroscopic properties are important characteristics of a material that is used in building construction. Wood is an anisotropic, heterogeneous and hygroscopic material. Given the cellular structure of wood as well as capillary action in the Lumina, the level of water uptake in wood is significant. Such amount of water uptake makes the wood susceptible to dimensional instabilities, causes alterations in the mechanical properties, and potential for degradation of the material. Various approaches have been investigated to modify the hydrophilic nature of lignocellulosic materials, including surface modifications using silane treatments, acetylation, wax etc. Although these surface modifications can decrease the rate of water uptake by the materials, the amount of water uptake at saturation remains unchanged. In fact, the lumen diameter is so small that the rise of liquid, even with a hydrophobic surface, can still occur. Therefore, the only way to halt the water uptake driven by capillary action in lignocellulosic materials is to apply a uniform cover on the material surface in addition to filling the lumen with dense material. In the current research project, the vascular structure of softwood (Spruce) is obstructed by silica nanoparticles using the impregnation technique as one of the advanced methods to reduce the water absorption capacity in wood. This process can form a thin film of nanoparticles on solid objects with complex geometries. In addition, the technique can fill up the cavities and voids of porous materials and prevent the capillary action inside the Lumina. In this method, the wood specimen is dipped into the solution, silica 40 (wt. %) colloidal solution. Then the solvent is evaporated which results in the formation of nanoparticles in the form of thin films or particulates. The former may change the moisture absorption on the surface and the later reduces the capillarity of the vascular system. This project aims to find the optimal impregnation condition to minimize the water uptake capacity of wood in order to increase wood physical and mechanical stabilities. Three immersing times (i.e. short, medium, and long) were used to coat wooden samples with the silica colloidal solution. The samples were conditioned in wet environments with specificiii relative time and then their weight as percentage change were examined. To investigate the capability of the method to obstruct the vascular structure of the wood samples, the characteristic process was done in the next step by some common tests such as X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Water Contact Angle (WCA), etc. The results from the experiments show that dip-coating the wood samples with silica nanoparticle colloidal solution had effect on the amount of water absorption, but significant levels of reduction in water attraction was achieved with considering the other effective parameters such as duration of each set, the number of sets that are conducted, and impregnation in vacuumed condition. More research is needed to quantify the benefits of using nanoparticle in these applications.

The unveiling of neutrino oscillation from observing the change in solar neutrino flux triggered physicists’ interest in studying the nature of the neutrino mass. The prevailing theory of explaining the tiny neutrino mass is called the “see-saw” mechanism, which postulates that the neutrino flavor eigenstate is the mixing between mass eigenstate of active neutrinos of a small mass and (left-) right-handed “sterile” (anti-)neutrinos of a large mass. The sterile neutrino is believed to be a new physics beyond the Standard Model, which can explain many other outstanding physical problems, like warm dark matter, asymmetry of baryon, etc. The HUNTER (Heavy Unseen Neutrinos from the Total Energy-momentum Reconstruction) experiment is a collaboration for searching for keV-mass range sterile neutrinos, and brings together an interdisciplinary team of researchers from Temple University, UCLA, Princeton University and the University of Hustonto develop an apparatus capable of searching for sterile neutrinos with high precision. In the HUNTER proposal, the radiation source generating neutrinos will be a cloud of atoms laser cooled and suspended by laser beams, the decay products except neutrinos will be detected by corresponding detectors, and their initial vector momenta will be reconstructed from the data recorded by the corresponding detectors. The missing mass in the decay, taken away by the neutrino, can then be evaluated from the energy and momentum conservation. The radiation sources of electron-capture decay are preferred for laboratory neutrino experiments because of the absence of energetic electrons in the decay products. 131-Cs is chosen by HUNTER to study the sterile neutrino mass and the mixing between sterile neutrinos and active neutrinos because of its short lifetime, simply decay products, and its alkali element spectral structure which enhances laser cooling and trapping. The Phase 1 HUNTER experiment targeting sterile neutrinos in the range 20-300 keV/c^2 requires the design of spectrometers with momentum resolution of a part in a thousand or better. To detect a 131-Xe ion, a spectrometer consisting of numbers of annular electrodes has been designed. The potentials of the electrodes of the ion spectrometer were carefully optimized to form an electrostatic lens, with time focusing and spatial focusing to achieve a high momentum resolution for ions despite the extended source presented by the magneto-optical trap. The optimization algorithm presented in this dissertation achieves a momentum precision of ∼0.12% (∼0.03%) for the high acceptance (high resolution) tune. An electron spectrometer was designed without “double focusing” for detecting the electrons produced in 131 Cs decays. The electron trajectories are guided by a uniform electric and magnetic field. An octagonal shaped, magnetic shield was designed to diminish the influence of external magnetic fields on the electron trajectories. The achieved electron momentum resolution is ∼0.1 keV including extended source effects, sufficient for the desired missing mass resolution. Other issues like the systematic errors of the ion spectrometer and the eddy current induced in the electrodes by periodically switching on/off the anti-Helmholtz coils of the magneto-optical trap were studied. The deformation of the spectrometer under its gravity was simulated using Autodesk Inventor. / Physics

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We set a preliminary 95% C.L. exclusion on the oscillation frequency of [special characters omitted] mixing using a sample of 400,000 hadronic Z 0 decays collected by the SLD experiment at the SLC during the 1996–98 run. In this analysis, [special characters omitted] mesons are partially reconstructed by combining a fully reconstructed Ds with other [special characters omitted] decay products. The Ds decays are reconstructed via the &phis;π and K*K channels. The b-hadron flavor at production is determined by exploiting the large forward-backward asymmetry of polarized Z0 → bb¯ decays as well as information from the hemisphere opposite to the reconstructed B decay. The flavor of the [special characters omitted] at the decay vertex is determined by the charge of the D s. A total of 361 candidates passed the final event selection cuts. This analysis excludes the following values of the [special characters omitted] mixing oscillation frequency: Δms < 1.4 psec−1 and 2.5 < Δms < 5.3 psec−1 at the 95% confidence level.

Fueled by a recent conjecture of D. Bessis that non-Hermitian, [special characters omitted] symmetric Hamiltonians have positive and real energies, the study of such theories has recently received much attention. Most of the work has been done in the context of quantum mechanics. Several techniques have been used up to date, including numerical and variational approaches. Field theoretic techniques have also been used, but always applied to one dimensional theories. This class of quantum field theories is isomorphic to quantum mechanics. In this dissertation we present the first study of a non-Hermitian, [special characters omitted] symmetric quantum field theory. We apply the methods of Modal Field Theory and Quasy-sparse Eigenvector Diagonalization to the study of a scalar quantum field theory with a cubic interaction and an imaginary coupling constant. The spectrum is examined and found to be real and positive. The vacuum expectation value of the field is imaginary and shows a peak in the nonperturbative regime. The physical mass is found to increase monotonically with the coupling strength.

In this thesis we present three research projects in classical General Relativity and Cosmology. In the first part of the thesis we investigate the definition of gravitational charge corresponding to the asymptotic boost symmetry of a spacetime and derive its role in the first law of black hole thermodynamics. In the cosmology part, we investigate the role of a scalar field in the early and late time evolution of the Universe. We find out observational constraints on the pseudo Nambu Goldstone Boson quintessence model using the latest supernova and Cosmic Microwave Background (CMB) data. In an attempt to explain a particular anomaly in the latest CMB data, we propose a modification to the standard single field inflation based on the initial kinetic energy domination with anisotropic initial conditions. Predictions of this mechanism can be tested in future data analysis.

This dissertation describes the measurement of asymmetries in neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of 383 million ϒ(4 S) → BB¯ decays collected between 1999 and 2006 with the BABAR detector at the PEP-II asymmetric-energy B factory located at the Stanford Linear Accelerator Center, California. The maximum likelihood fit that incorporates kinematical, event-shape, and particle identification information is used to measure the CP asymmetries in B0 → π +π− and K± π∓ decays. The direct CP-violating asymmetry between decays to K−π + is AKπ = −0.107 ± [special characters omitted]. The time-dependent CP-violating parameters in B0 → π+π− decays are Sππ = −0.60 ± 0.11 ± 0.03, Cππ = −0.21 ± 0.09 ± 0.02. For all the measurements above, the first error is statistical and the second is systematic.

We have measured the polarization of $\Lambda\sp\circ$'s produced in the diffraction dissociation process $p\ +\ p\ \to\ p\ +\ \Lambda\sp\circ\ +\ X$ at 800 GeV/c using two million diffractive inclusive and 58,000 exclusive $\Lambda\sp\circ$ events. The $\Lambda\sp\circ$ kinematic variables in our data sample only have weak correlations. For the diffractive inclusive sample, we have studied the dependence of the $\Lambda\sp\circ$ polarization on the following variables: (1) $\Lambda\sp\circ$transverse momentum; (2) $\Lambda\sp\circ$ Feynman x; (3) missing mass squared of the beam system; and (4) event charge multiplicity. Our diffractive inclusive results agree well with the existing world results on inclusive $\Lambda\sp\circ$ polarization. We do not see a strong dependence on the missing mass squared of the beam system or event charge multiplicity. For the exclusive sample, we have studied two fully reconstructed reactions of the form p + p $\to$ p + $\Lambda\sp\circ$ + $K\sp+$ + ($\pi\sp+\pi\sp-)\sp{n}$, n = 1, 2 and the topology dependence of the polarization. Within the statistical uncertainties, the $\Lambda\sp\circ$ polarization does not depend on the final state. Our results show that the $\Lambda\sp\circ$ polarization of the exclusive sample is consistently larger than that of the diffractive inclusive sample, although the uncertainties are large. The study using exclusive events enables us to account for all possible backgrounds and to minimize the dilution of $\Lambda\sp\circ$'s from $\Sigma\sp\circ$ decays and resonance productions. These analyses represent the first study of the $\Lambda\sp\circ$ polarization in diffraction dissociation at 800 GeV/c. It is also the first study of the topology, missing mass squared and event charge multiplicity dependence of $\Lambda\sp\circ$ polarization at this energy.

The structure function of a virtual photon, representing the physics of the hard scattering of an electron off a massive photon target resulting in a hadronic final state, has been measured in the kinematic range $1.5\le Q\sp2\le 5.5\ {\rm GeV}\sp2,\ 0.1\le P\sp2\le 1.5\ {\rm GeV}\sp2$ and $2\le W\le 20$ GeV. The measurement was done using the TPC/Two-Gamma detector facility and employs a heretofore unique method to determine the W of the final state by using information from both the visible mass of the final state as well as the mass reconstructed from the two lepton tags. The results are compared to a variety of models, and are found to be consistent with an incoherent sum of the QPM and VDM models. In addition, the structure function of the virtual photon has been measured in the kinematic range $10\le Q\sp2\le 50\ {\rm GeV}\sp2, 0.1\le P\sp2\le 1.5\ {\rm GeV}\sp2,$ a heretofore unexplored region. The results are somewhat high, though statistically consistent with being physically allowed. The results might indicate the presence of an interesting background, or perhaps physics that has not yet been accounted for in the comparison to model expectations.

QCD inspired models are used to study the existence of correlations among quarks in hadronic matter at high densities. Specifically it is seen that pairs of quarks are correlated in high density hadronic matter, leading to the existence of diquarks at intermediate densities. A possible experimental signal for the diquarks is suggested. Similar techniques are used to understand 'anomalous' behavior of Pionic Atoms.