No description available.

No description available.

Most of this thesis describes experiments conducted in order to generate soft x-rays of energy >67 eV from a laser-generated plasma, in order to pump the Xe III Auger laser at 109 nm. In attempts to obtain the optimal sub-nanosecond laser pulses for amplification in a very simple KrF (248 nm) laser a compact KrF oscillator was used to obtain 1 ml pulses of FWHM duration 2 ns, and plasma-truncated reflection of a focused KrF beam from metal targets gave 1.8 ns pulses. Longer pulses were obtained by truncated stimulated Brillouin scattering (TRUBS), and by plasma-truncated spatial-filtering. Experiments were conducted to pump the Xe III laser using the leading edge of a 20 ns KrF laser pulse. An off-axis spherical mirror produced a 3 cm line plasma on a tantalum target. A poor conversion efficiency to soft x-rays was observed. Unexpectedly poor KrF beam quality was shown to have been a potential cause, a fault in the detection system having been ruled out. A repeat experiment was started, employing tighter focusing and better KrF beam quality. A 7 ps KrF laser system was also investigated for the generation of the necessary plasmas. No 109 nm lasing was observed, and a low conversion efficiency into soft x-rays was measured. The short duration of the KrF pulse was suspected as the cause, and some attempts were made to compensate for this by means of preformed plasmas. Over the course of the work, several aspects of KrF laser technology were improved, including: the characterisation of a novel, safe, solid-state source of fluorine (F₂); the quantitative characterisation of nitrogen dioxide (NO₂) as a variable attenuator for KrF radiation; and the manufacture of uniform, transparent, electrodes led to the laser system having the highest single pulse energy (2.55 J) of any UV-preionised, discharge-excited, conventional-aperture KrF laser. Finally, separate work led to the development and absolute characterisation of a laser-plasma source of tunable VUV/EUV/XUV radiation (30 nm to 200 nm; 6 eV to 41 eV), as well as a sodium salicylate scintillator-based detection system. After optimisation of the target material, laser focusing, and micro-channel-plate (MCP) focusing of the plasma emission, an output of between 10⁶ and 10⁷ photons per shot in a 4 nm bandwidth could be delivered on target.

The distributions of neutron star and black-hole masses are analyzed to provide constraints on models of the neutron star equation of state. Inclinations obtained from ellipsoidal analysis and the excess noise seen in SXT light curves, are discussed.

Study of structure and interface morphology of magnetic thin films is crucial in obtaining a better understanding of the coupling mechanisms in such systems. In this thesis various x-ray scattering techniques are applied to a series of Co/Cr trilayers, Cu/Co multilayers and spin valve structures. It is demonstrated that modifications to the distorted wave Born approximation allow the modelling of grazing incidence diffuse scatter originating from graded systems such as Co/Cr. Grazing incidence scattering techniques are also employed to investigate the out of plane correlations of lateral roughness in Cu/Co multilayers, as well as in miscible trilayer structures. The use of soft x-rays in the investigation of 3d transition metal multilayers is also presented. Such experiments are sensitive to the component of magnetisation aligned with the direction of the incident beam. In a series of magnetisation experiments, the dependence of the x-ray scatter sensitive to this component of magnetisation are analysed. For the first time evidenced is found for correlated magnetic roughness, which has lateral correlation lengths far greater than the structural roughness length scales. This magnetic roughness is measured in detail, and the correlation length is found to vary with applied field direction. Grazing incidence x-ray fluorescence is applied to two spin valve structures. These experiments provide a direct measure of buried layer thicknesses which is not possible by other x-ray scattering techniques. This novel method for the determination of the copper layer thickness in spin valves shows the versatility of non-destructive x-ray methods for the characterisation of magnetic metallic multilayers.

No description available.

The outcome of several studies into future X-ray astronomy satellite missions has favoured the approach of using grazing incidence optics in conjunction with Charged Coupled Devices (CCD's) as focal plane detectors. This approach allows astrophysical investigation of unprecedented sensitivity by maximising source detectability and by resolving the source spectra. This thesis covers work performed in the development and evaluation of EEV CCD's for use as focal plane X-ray detectors. Due to the nature of the space environment, the interactions of radiation with CCD's also form a major part of this thesis. The subject of X-ray astronomy is introduced and the considerations affecting the operation of CCD's in space are discussed. The construction and operation of the CCD is thoroughly reviewed. The equipment and techniques used to evaluate the performance CCD's to X-rays are presented. A model is developed to simulate the interaction of X-rays with CCD's and this is followed by detailed measurements of X-ray performance. Further improvements to the design of CCDs to optimise their use as X-ray detectors are also discussed. These improvements include increased high and low energy quantum efficiency, larger area, low noise, reduced dark current and increased tolerance to radiation damage. Sources of background signal are investigated which lead to background rejection schemes for different CCD designs. Modelling is also performed to simulate an application of CCD's in space. Measurements of the radiation damage suffered by the CCD's are given and the damage mechanisms which will ultimately lead to device failure in space are discussed. The radiation damage covers irradiation using Co60 and heavy ions, but focuses on the effects of protons of doses below 5 krads. The impact of such a fluence on the scientific performance of an X-ray satellite is evaluated.

No description available.

This thesis describes the observation of a number of astronomical objects using the University of Durham Atmospheric Cerenkov light detectors. The array of telescopes was used to study the Very High Energy (V.H.E.) gamma-radiation from these objects from June 1981 until November 1984.The general features of Gamma-ray astronomy are briefly discussed, and a review of the main results of previous gamma-ray observations is given. The basic theory and general characteristics of Atmospheric Cerenkov Effect experiments are reviewed. Details of the design, operation and performance of the University of Durham facility are presented in addition to details of the improvements achieved in the development of a new telescope. In particular, the new optical system is described. The main analysis procedures are explained. The adaptation of statistical techniques used to analyse the intensity of the Cerenkov light flash is described in some detail. A discussion of the problems involved in conducting an extensive search for periodicity in the data collected from Cygnus X-3 is given. A procedure for testing for transient pulsed gamma-ray emission from the Crab Pulsar is also described. The results of the observations from several objects are presented., the binary X-ray sources, Cygnus X-3, Hercules X-l and 4U0115+63, the Crab pulsar and the Galactic Plane. In addition, the preliminary results from observations of seven radio pulsars and seven other objects are given. A review of the main production mechanisms of V.H.E. gamma-radiation is given with particular emphasis on the models proposed for the high energy processes in Cygnus X-3, other binary-ray sources and pulsars.

Includes bibliographic references (8 p.) / x, 167 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The results of observations of four potential gamma-ray sources with the CANGAROO and BIGRAT imaging Cherenkov telescopes. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1999