Optimizing the performance of an atmospheric Cherenkov telescope
This thesis is concerned with the performance of the Mark 6 atmospheric Cherenkov telescope, which is the latest triple-coincidence VHE gamma-ray telescope built by the Durham group. Chapter 3 describes the Durham telescopes, with particular reference to the Mark 6 telescope. It goes on to describe the procedures which are involved in taking and processing data and the subsequent analysis of such data using imaging techniques to distinguish between gamma-rays and the cosmic-ray background. The quality and quantity of data recorded are dependent upon the performance of various components of the telescope and also on the environment in which it operates. Chapter 4 discusses the effects of such parameters on the performance of the telescope and describes the efforts made to minimize the variations in the data caused by changes in these conditions. Chapter 5 describes the improvements made to the telescope design and operation post-construction ui order to increase the rate of data acquisition and to improve the quality of the data, particularly with a view to enhancing the telescope sensitivity to low energy gamma-rays. Data taken with 2 separate and simple light collectors/detectors can be combined to use differences in the distribution of light from gamma-ray and hadronic induced showers to discriminate between them. Chapter 6 contains the results of such a study of the stereoscopic properties of Cherenkov signals using the Durham Mark 6 and Mark 5A telescopes and highlights the use of data taken using the well-separated left and right detectors of the Mark 6 telescope for a similar purpose. The final chapter reviews the achievements to date in terms of the improvements made to the telescope and the sources detected during its operation. It goes on to describe future developments to further enhance the telescope performance.