Edgar, Michael Leonard; (1993) A high performance, microchannel plate based, photon counting detector for space use. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

This thesis describes the development of a microchannel plate (MCP) based photon counting detector using the Spiral Anode (SPAN) as a readout. This detector was one of two being evaluated for use in the Optical Monitor for ESA's X-ray Multi Mirror satellite. Throughout this thesis, where possible, the underlying physical processes, particularly those of the MCP, have been identified and studied separately. The first chapter is an introduction to photon counting detectors and includes a review of the various readouts used with MCPs. The second chapter provides a more detailed review and analysis of cyclic, continuous-electrode, charge-division readouts, of which SPAN is an example. The next two chapters describe the technique for measuring the radial distribution of the MCP charge cloud, which can significantly affect detector imaging performance. Results are presented for various operating conditions. The distribution consists of two parts and the size is dependent on the operating voltages of the MCP stack. The fifth and sixth chapters describe the procedure for operating a SPAN readout and the decoding necessary for converting the ADC readings into a two dimensional coordinate. Various methods are described and their limitations evaluated. The cause of problems associated with the SPAN readout, such as "ghosting" and fixed patterning and methods of reducing them are discussed in detail. Results are presented which demonstrate the performance of the anode. The seventh chapter discusses and evaluates the interaction between channels in MCPs and the long range effects an active pore has on the surrounding quiescent pores. This represents the first time that these effects have been measured. The importance of this phenomenon for imaging detectors is discussed and possible mechanisms evaluated. The last chapter presents the conclusions of this work and discusses the suitability of SPAN detectors for use on satellites.

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