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The sources of ultra high energy cosmic rays (UHECRS) have remained undetected for over half a century. Identifying these sources could be made easier by measuring the charge and thus mass of UHECRs, as this would allow for corrections in their arrival directions due to deflections introduced by intervening magnetic fields to take place. The aim of this thesis is to derive a parameter which can be used as a surrogate for depth )f maximum in the data obtained using the surface array of the Auger Observatory for the measurement of the mass composition of UHECRs.

The highly relativistic particles that arrive at the Earth, the long studied yet enigmatic cosmic rays, include >TeV electrons as well the dominant protons and nuclei. As during their diffusion in the interstellar medium these electrons undergo severe energy losses through both synchrotron and inverse Compton processes they are hence only able to travel relatively short distances. Therefore measurement of the spectrum of these electrons is able to give an important insight into the local distribution of cosmic ray sources. The use of IACTs to measure the highest energy electrons has already been pio- neered with the current generation of instruments such as HESS. This thesis describes the steps required to build upon these results and produce a measurement of the highest energy (>10 TeV) electrons, by use of the next generation ground-based gamma-ray telescope the Cherenkov Telescope Array. The first step in this process was the investigation of the systematic uncertainties in the modelling of high energy hadronic interactions and the resulting effect on the observable properties of the resulting air shower. This investigation was followed by the development of a new IACT event analysis chain, including improvements to both the event reconstruction and background rejection. The point source sensitivity of CTA candidate arrays could be increased up to 30% compared to the traditional chain. This chain was then applied to cosmic electrons and the sensitivity of CTA to electrons was determined. A simple semi-analytical model was then produced to demonstrate that signatures in the high energy electron spectrum from local sources are highly likely and should be observable with CTA at a high significance level

Bibliography: leaves 138-153 / xi, 153 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1989

This thesis presents theoretical work on the propagation of ultra high energy cosmic rays, from their source to Earth. The different energy loss processes, resulting from cosmic ray interactions with the radiation fields, are addressed. The subsequent uncertainties in the energy loss rates and the effect produced on the arriving cosmic ray spectrum are highlighted. The question of the composition of ultra high energy cosmic rays remains unresolved, with the range of possibilities leading to quite different results in both the secondary fluxes of particles produced through cosmic ray energy loss interactions en route, and the arriving cosmic ray spectra at Earth. A large range of nuclear species are considered in this work, spanning the range of physically motivated nuclear types ejected from the cosmic ray source. The treatment of cosmic ray propagation is usually handled through Monte Carlo simulations due to the stochastic nature of some of the particle physics processes relevant. In this work, an analytic treatment for cosmic ray nuclei propagation is developed. The development of this method providing a deeper understanding of the main components relevant to cosmic ray nuclei propagation, and through its application, a clear insight into the contributing particle physics aspects of the Monte Carlo simulation. A flux of secondary neutrinos, produced as a consequence of cosmic ray energy loss through pion production during propagation, is also expected to be observed at Earth. This spectrum, however, is dependent on several loosely constrained factors such as the radiation field in the infrared region and cosmic ray composition. The range of possible neutrino fluxes obtainable with such uncertainties are discussed in this work. High energy cosmic ray interactions with the radiation fields present within the source may also occur, leading to cosmic ray energy loss before the cosmic ray has even managed to escape. The secondary spectra produced are investigated through the consideration of three candidate sources. A relationship between the degree of photo-disintegration in the source region and the neutrino flux produced through p γ interactions is found.

Bibliography : leaves i-xx / xi, 168, [99], xx leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1991