Polarimetry is one of the principal means of investigating the interaction of light with matter. Theoretical models and experimental techniques are presented in this dissertation for polarimetric characterization of random electromagnetic beams and of signatures of random media in different scattering regimes and configurations. The degree of polarization rather than the full description of the state of polarization is of interest in multiple scattering and free space propagation where the statistical nature and not the deterministic component of light bears the relevant information. A new interferometric technique for determining the degree of polarization by measuring the intensity fluctuations in a Mach-Zehnder interferometric setup is developed. For this type of investigations, one also needs a light source with a controllable degree of polarization. Therefore, also based on a Mach-Zehnder interferometer, we proposed a new method for generating complex random electromagnetic beams. As a direct application of the cross-spectral density matrix formalism, it is shown that the spectral and the polarimetric characteristics of light can be controlled by adjusting the correlations between parallel components of polarization propagating through the two arms of the interferometer. When optical beams are superposed in the previous applications it is desirable to understand how their coherence and polarimetric characteristics are combined. A generalization of the interference laws of Fresnel and Arago is introduced and as a direct application, a new imaging polarimeter based on a modified Sagnac interferometer is demonstrated. The system allows full polarimetric description of complex random electromagnetic beams. In applications such as active illumination sensing or imaging through turbid media, one can control the orientation of the incident state of polarization such that, in a given coordinate system, the intensities are equal along orthogonal directions. In this situation, our novel interferometric technique has a significant advantage over standard Stokes imaging polarimetry: one needs only one image to obtain both the degree of polarization and the retardance, as opposed to at least three required in classical Stokes polarimetry. The measurement of the state of polarization is required for analyzing the polarization transfer through systems that alter it. Two innovative Mueller matrix measurement techniques are developed for characterizing scattering media, either in quasi real-time, or by detection of low level signals. As a practical aspect of Mueller polarimetry, a procedure for selecting the input Stokes vectors is proposed. The polarimetric signatures of different particulate systems are related to their structural properties and to the size distribution, shape, orientation, birefringent or dichroic properties of the particles. Various scattering regimes and different geometries are discussed for applications relevant to the biomedical field, material science, and remote sensing. The analysis is intended to elucidate practical aspects of single and multiple scattering on polydisperse systems that were not investigated before. It seems to be generally accepted that depolarization effects can only be associated to multiple scattering. It is demonstrated in this dissertation that depolarization can also be regarded as an indication of polydispersity in single scattering. In order to quantify the polarizing behavior of partially oriented cylinders, the polarization transfer for systems consisting of individual layers of partially aligned fibers with different degrees of alignment and packing fractions is also analyzed in this dissertation. It is demonstrated that a certain degree of alignment has the effect of a partial polarizer and that the efficiency of this polarizer depends on the degree of alignment and on the packing fraction of the system. In specific applications such as long range target identification, it is important to know what type of polarization is better preserved during propagation. The experimental results demonstrate that for spherical particles smaller than the wavelength of light, linear polarization is better preserved than circular polarization when light propagates through turbulent media. For large particles, the situation is reversed; circular polarization is better preserved. It is also demonstrated here that this is not necessarily true for polyhedral or cylindrical particles, which behave differently. Optical activity manifests as either circular birefringence or circular dichroism. In this dissertation, a study is presented where both the effect of optical activity and that of multiple scattering are considered. This situation is relevant for medical applications and remote sensing of biological material. It is demonstrated here that the output state of polarization strongly depends on the optical density of the scattering medium, the optical rotatory power and the amount of circular dichroism associated to the scattering medium. This study shows that in the circular birefringence case, scattering and optical activity work together in depolarizing light, while in the dichroic case the two effects compete with each other and the result is a preservation of the degree of polarization. To characterize highly diffusive media, a very simple model is developed, in which the scattering is analyzed using the Mueller matrix formalism in terms of surface and volume contributions.

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In this work we present the basic theoretical concepts of the description of the nucleon spin structure. The theoretical background of two processes of interest - Semi-inclusive DIS and Drell-Yan - in the terms of Transverse Momentum De- pendent Parton distribution Functions is presented. The COMPASS experiment and particularly its unique polarised target are described in detail. Several target related measurements are presented. The express analysis and detector efficien- cies analysis are presented as examples of important hardware related analysis. Finally two measurements of Transverse Spin Asymmetries are presented. The first measurement is the measurement of the Transverse Spin Asymmetries in J/ψ production in the Semi-inclusive DIS on polarised protons. The second mea- surement is the measurement of Transverse Spin Asymmetries in J/ψ in the π− p polarised Drell-Yan data. 1

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Experiments with polarized "ultracold neutrons" (UCN) offer a new way to measure the decay correlations of neutron beta decay; these correlations can be used to test the completeness of the Standard Model and predict physics beyond it. Ultracold neutrons are very low energy neutrons that can be trapped inside of material and magnetic bottles. The decay correlations in combination with the neutron and muon lifetimes experimentally find the first element (Vud) of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. The CKM matrix is a unitary transform between the mass and weak eigenstates of the d, s and b quarks; if the matrix is not unitary this would imply that the Standard Model is not complete. Currently the first row of the CKM matrix is over 2 sigma from unitarity and Vud is the largest component of the row. The UCNA experiment looks at the correlation between the polarization of the neutron and the momentum of the electron resulting from the beta decay of the neutron (the A-correlation). The keys to making a high precision measurement of A-correlation are a near 100% polarization of the neutrons that decay, low"backscatter electron detectors, and small, well characterized backgrounds. UCN can be 100% polarized by passing them through a seven Telsa magnetic field. The key to the UCNA experiment is keeping them polarized until they decay or are lost. This dissertation covers the development of guides that are minimally depolarizing and efficient transporters of UCN and their use in the UCNA experiment. The entire guide development process is covered from conception to manufacturing and testing. This process includes development of a pulsed laser deposition, diamond-like carbon coating system and materials studies of the resulting coatings. After the initial studies of the guide coating, meter"long sections of guide are tested with UCN to determine their depolarization and transport properties. The guide technology developed in this dissertation has been used in the entire UCNA experiment. Also, this technology is currently the state of the art for polarized and non-polarized UCN guide systems and it is being implemented in several new UCN experiments. / Ph. D.

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This thesis presents a set of measurements of spin asymmetries from the heavy atoms krypton and rubidium. These investigations allow examination of the spin orbit interaction for electron scattering from the target atoms. These measurements utilise spin polarized electrons in a crossed beam experiment to measure the Sherman function from krypton and the A2 parameter from the 52P state of rubidium. The measurements utilise a new spin polarized electron energy spectrometer which is designed to operate in the 20-200 eV range. The apparatus consists of a standard gallium arsenide polarized electron source, a 180 degrees hemispherical electron analyser to detect scattered electrons and a Mott detector to measure electron polarization. A series of measurements of the elastic Sherman function were performed on krypton at incident electron energies of 20, 50, 60, 65, 100, 150 and 200 eV. Scattered electrons are measured over an angular range of 30-130 degrees. These measurements are compared with calculations of the Sherman function which are obtained by solution of the Dirac-Fock equations. These calculations include potentials to account for dynamic polarization and loss of flux into inelastic channels. At the energies 50, 60 and 65 eV, experimental agreement with theory is seen to be extremely dependent on the theoretical model used. Measurement of the A2 parameter from the combined 52P1/2,3/2 state of rubidium are performed at an incident energy of 20 eV. The scattered electrons are measured over an angular range of 30-110 degrees. This measurement represents the first such measurement of this parameter for rubidium. Agreement with preliminary calculations performed using the R-matrix technique are good and are expected to improve with further theoretical development.

The novel designs of circular microstrip antennas have been investigated in this dissertation. In the linearly polarized designs, the study of single-feed dual-frequency circular microstrip antenna with an open-ring slot has been firstly presented. As for the broadband circular microstrip antenna designs, antennas with two open-ring slots, embedded reactive loading by probe feed and microstrip-line feed have been presented. The antenna bandwidth of them can be enhanced about 4% to 6%. In the circularly polarized designs, we have proposed a circularly polarized microstrip antenna with a spur line. By choosing a suitable length of the spur line, CP operation can be obtained. And then, such a design can be applied to a compact circular patch antenna with bent slots. These reduced the antenna size to be 40%~50% of that of the simple case. Finally, we use the ideas of CP operation with elliptic patch and dual-frequency operation with stacked patch to propose a dual-band circularly polarized stacked elliptic microstrip antenna design. The frequency ratio of this design is about 1.39.