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Title: Sybchrotron calibration of microchannel plate detectors for X-ray astronomy
Author: Pearce, Sarah Elizabeth
Awarding Body: University of Leicester
Current Institution: University of Leicester
Date of Award: 1998
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This thesis describes the calibration of CsI- and KBr-coated microchannel plate (MCP) detectors using the Daresbury Synchrotron Radiation Source (SRS). This work was carried out as part of the calibration programme for the Advanced X-ray Astrophysics Facility (AXAF). The AXAF High Resolution Camera (HRC) consists of two MCP detectors: HRC-I, optimised as an imaging detector, and HRC-S, optimised as the read-out detector for a dispersive spectrometer. Accurate knowledge of the MCP quantum efficiency (QE) variation with energy is particularly important for HRC-S so that atomic absorption edge-related features in the MCP glass and photocathode are not misinterpreted as emission features in astrophysical spectra. The MCPs were calibrated on three beamlines at the SRS, which covered the energy ranges 50-350eV, 250-1400eV and 2-6keV. Calibration included measurement of QE as X-ray energy and incidence angle were varied. The ratio of the QE of CsI- and KBr-coated MCPs was also determined and gain decay of the MCPs was measured as charge was abstracted from a small area. Several significant features in QE were noted, a number of which exhibited characteristics such as white lines, slow onset and energy shifts. There were however, problems with measurement of the monochromator responses at the SRS, which cast doubt upon the accuracy of the QE-energy curves produced. The variation of QE with energy and angle measured at Daresbury was modelled. An existing model was updated to take account of the channel bias angle and was able to reproduce the general features of the QE-energy curves. An attempt was then made to model linear absorption coefficient and hence reproduce the white lines visible on some of the edge-related QE features. The final part of the thesis considers and models the effect of thermal annealing upon the QE of CsI-coated MCPs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available