The ultimate aim of this work is to develop a laboratory model of large area, xenon-filled, proportional counter, that has good spatial resolution in conjunction with optimum spectral resolution in the energy range 1 to 10 keV. The results of initial development on a 10cm x 10cm imaging counter are first described. The most important effect established in this work is the dependence of spatial resolution on the quench gas. This effect is also observed to be a function of detector size. The mechanism proposed is that secondary electrons liberated by UV photons from the avalanche cause fluctuations in the centroid position of the induced charge distribution. Space charge effects are also observed at the gains required for imaging, which implies that the detector is semi-proportional. This causes degraded energy resolution at the high gains that are used for imaging. The linearity of a xenon imaging counter is found to be poor in the axis perpendicular to the anode wire direction. The use of a long drift region and different quench gases are investigated together with their effect on linearity and spatial resolution in the axis perpendicular to the anode wire direction. Finally, the construction and evaluation of a large area counter 30cm square is described. It is shown that this device produces excellent results (spatial resolution of 1.2mm FWHM and an energy resolution of 27% at 6 keV). Methods of improving the performance of the instrument are also discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:349673 |
| Date | January 1984 |
| Creators | Thomas, Huw Densley |
| Publisher | University of Leicester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/2381/35808 |
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