Introduction: In this chapter the present status of our understanding of the interaction of five and fewer nucleons will be briefly summarized. Some of the gaps in our knowledge will be pointed out, making clear the motivation for the experimental work described in the remainder of the thesis. Since most of the experimental effort by the author has been directed towards scattering of neutrons by protons, the nucleon - nucleon problem will be considered in greater detail. In speaking of this, the simplest problem in nuclear physics, M.L. Goldberger made the following remarks at the 1960 Midwest Conference on Theoretical Physics: "There are few problems in modern theoretical physics which have attracted more attention than that of trying to determine the fundamental interaction between two nucleons. It is also true that scarcely ever has the world of physics owed so little to so many .. . . . . . In general, in surveying the field, one is oppressed by the unbelievable confusion and conflict that exists. It is hard to believe that many of the authors are talking about the same problem, or in fact that they know what the problem is."

A field system capable of making high-resolution measurements of rainfall is described. The system incorporates a disdrometer, an array of high-resolution raingauges, a general-purpose data acquisition system and ancillary equipment. In an evaluation of the disdrometer, a theory allowing calculation of the effects of windspeed on detection efficiency is presented which has wide applicability. The raingauges are an improved design allowing 10-s temporal resolution of rainfall intensity and 100 m spatial resolution of rain-patch size when used in the array. An extensive data base of measurements made using the field system is described. Duration of rainfall is shown to be approximately log-normal and is consistent with a log-normal distribution of precipitation region size. The fractional duration of rainfall above a threshold intensity varies considerably between rain periods, a result which may be important for electromagnetic attenuation models. Estimation of the shapes of rain patches using the raingauge array is demonstrated and shows considerable promise. Raindrop fallspeeds, measured using the disdrometer, generally show much less deviation from stagnant air terminal velocities than indicated by previously reported results. Much of the spread in the results is shown to be consistent with instrumentation errors although significant residual deviations are still apparent; the fallspeeds are generally slower than stagnant air values would suggest. Measurements of the arrival rate of raindrops at the disdrometer indicate clustering of drops rather than the often assumed Poisson distribution. The clustering is associated with small drops and has reasonable correlation with rainfall intensity. Examination of the cross-correlation of arrival rates of different sized drops show results in contradiction to previous results; small drops are found to lead other sized drops. Using a normalisation method, the shapes of raindrop size distributions measured are shown to be depressed in the mid-radius region.

In this thesis we study the Dicke model outside the rotating wave approximation (RWA), by employing phase space techniques and the quantum trajectory theory. We present a review of the basic models of open systems in quantum optics and present an experimental proposition justifying the model to be studied. We use the phase space approach to study, among other subjects, entanglement, squeezing and fluctuations across a quantum phase transition. Three different phase space representations are used and their strengths and weaknesses compared. The quantum trajectory theory is applied to visualise the global quantum fluctuations and to learn how different measurement schemes will affect the creation of entanglement. / The University of Auckland, Department of Physics.

In this thesis we study the Dicke model outside the rotating wave approximation (RWA), by employing phase space techniques and the quantum trajectory theory. We present a review of the basic models of open systems in quantum optics and present an experimental proposition justifying the model to be studied. We use the phase space approach to study, among other subjects, entanglement, squeezing and fluctuations across a quantum phase transition. Three different phase space representations are used and their strengths and weaknesses compared. The quantum trajectory theory is applied to visualise the global quantum fluctuations and to learn how different measurement schemes will affect the creation of entanglement. / The University of Auckland, Department of Physics.

In this thesis we study the Dicke model outside the rotating wave approximation (RWA), by employing phase space techniques and the quantum trajectory theory. We present a review of the basic models of open systems in quantum optics and present an experimental proposition justifying the model to be studied. We use the phase space approach to study, among other subjects, entanglement, squeezing and fluctuations across a quantum phase transition. Three different phase space representations are used and their strengths and weaknesses compared. The quantum trajectory theory is applied to visualise the global quantum fluctuations and to learn how different measurement schemes will affect the creation of entanglement. / The University of Auckland, Department of Physics.

In this thesis we study the Dicke model outside the rotating wave approximation (RWA), by employing phase space techniques and the quantum trajectory theory. We present a review of the basic models of open systems in quantum optics and present an experimental proposition justifying the model to be studied. We use the phase space approach to study, among other subjects, entanglement, squeezing and fluctuations across a quantum phase transition. Three different phase space representations are used and their strengths and weaknesses compared. The quantum trajectory theory is applied to visualise the global quantum fluctuations and to learn how different measurement schemes will affect the creation of entanglement. / The University of Auckland, Department of Physics.

is a major polysaccharide of the plant cell wall which is known to play a role in many mechanical functionalities, especially when a gel is formed in the presence of calcium. Understanding the gelling abilities of pectin is of great interest to the food industry also, since pectin is a widely used as a gelling agent and thickener. The aim of this study was to apply two complementary microrheological techniques to these systems, multiple particle tracking (MPT) and a light scattering technique called diffusing wave spectroscopy (DWS). While the first one provides fundamental information about the homogeneity of the studied gel, the second gives access to the high frequency behaviour, related to the nature of the basic strands of the network. Firstly, after verifying the validity of the experimental apparati and analysis approaches in a series of careful control experiments on archetypal systems, a regime where pectin gels exhibit the signatures of semi-flexible networks was identified in experiments carried out on gels made of pectin chains pre-engineered by enzymatic deesterification and subsequently assembled with the release of Ca2+. These results were the first showing that polysaccharides networks could be accommodated within the framework of semi-flexible networks, which have become a paradigm for biological gels, such as the well-known F-actin solutions present in the cell cytoskeleton. However, in the plant cell wall, where calcium is already present, the assembly mechanism could be controlled in a different manner, and a more biologically relevant system was studied where the action of the plant enzyme pectinmethylesterase was used to liberate ion-binding groups in the presence of Ca2+. Gels formed according to this alternative methodology were found to behave as punctually cross-linked flexible networks, strikingly different from the first results. This would be explained by the presence of short blocks of charged residues. Finally, experiments on pectins carried out with controlled blocky structures showed that a pectin made of short blocks can exhibit both sorts of network, depending on the polymer and Ca2+ concentrations. This lead naturally to the construction of a state diagram for the regimes of assembly, with proposed control parameters being the polymer concentration and the ratio of the amount of Ca2+ to the quantity of pectic residues which can effectively bind the calcium into cross-links, christened Reff.

No description available.

The proton polarization in the 3He(d,p)4He reaction induced by unpolarized deuterons has been measured at deuteron lab. energies of 2.0, 2.8, 3.9 and 6.0MeV for 20 angles between 0° and 150° (c.m.). Statistical uncertainties are typically ± 0.01. The measurements were made with a proton polarimeter in which the left-right asymmetry of scattering at 60° (lab.) in 4He is determined. The polarimeter employs "venetian-blind" collimation of the protons by conical vanes and 75 cm2 plastic scintillator detectors. Four detectors are included for use in polarization transfer experiments. For 10.5 MeV protons and a helium pressure of 250 p.s.i. the target thickness is 3 MeV and the efficiency per detector per unpolarized proton incident is 10-4. For each polarimeter detector a triple coincidence with a 15 ns resolving time was required with two scintillator transmission detectors preceding the polarimeter. Spectra of random coincidences were accumulated simultaneously and subtracted. Asymmetries resulting from polarimeter-target misalignment and other geometrical effects are discussed. All results quoted are geometric means of pairs of measurements for 180° rotation of the polarimeter and are also arithmetic means of such measurements to left and right of the 3He target. The absolute analyzing power is estimated by computer simulation of trajectories to be -0.638 ± 0.020 for protons entering at 10.3 MeV. The product of polarization and cross section is fitted to an expansion of first-order associated Legendre polynomials using these results and earlier measurements. Only four terms are required except at 6.0MeV where a fifth is necessary. The energy dependence of these coefficients suggests resonances in 5Li at deuteron energies of 60MeV (odd coefficients) and 7.5 MeV (even coefficients) in agreement with results for the polarized-beam analyzing powers(1). Comparison of the results with vector-polarized-beam (1) and polarized-target(2) analyzing powers shows no evidence for the postulated simple relations(3) based on DWBA cal calculations. Comparison of the results with recent measurements of the neutron polarization in the mirror reaction(4) shows no significant differences. The theory of angular correlations in charged particle reactions is developed and used to calculate outgoing nucleon polarizations. Expressions are given for polarization transfer coefficients. These coefficients are evaluated in terms of the T-matrix elements for the interference of various channels with the dominant S-wave, JΠ = 3+/2 channel in 3He(d,p)4He at the 0.43 MeV resonance. Two experiments to measure combinations of these elements are discussed. (1) Gruebler, W. et al., 1971, Nucl. Phys. Al76, 631 (2) Leemann, Ch., W. Gruebler et al., 1971, in Polarization Phenomena in Nuclear Reactions (University of Wisconsin Press), p. 548 (3) Tanifuji,M. and K. Yazaki, 1968, Prog. Theor. Phys. 40, 1023 (4) Mutchler, G.S., W.B. Broste and J.E. Simmons, 1971, Phys. Rev. C3, 1031

It is well known that the ionosphere is not a uniform and homogeneous medium. For many years studies have been made of ionospheric irregularities down to sizes of less than 1 km; some of which are associated with periodic motion caused by gravity waves, others, with turbulence phenomena. The effect of these ionospheric disturbances on conventional high-frequency radio communication links is an important study, and extends back to almost the beginning of ionospheric investigations. It is now recognised, in fact, that the Ionosphere behaves as an irregular reflector which imposes fluctuations on initially plane wavefronts as they, emerge from the medium.