An investigation of some techniques for the localisation of ionizing radiation

• Main Author: Hough, James
• Published: University of Glasgow 1970
• Subjects: QC Physics
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.768653

The research carried out was on the development and study of position sensitive proportional counters and was initiated by Dr. R.W.P, Drever. The first chapter of this thesis is a discussion of the type of experimental problems which require the spatial distribution of ionizing radiation to be investigated and of the different methods of obtaining position information. The possible advantages of a proportional counter system for the localisation of charged particles and love energy x-rays are pointed out. In the following chapter, the main factors which limit the position resolution of any electrical detector are outlined, with particular emphasis on the effect of the thermal diffusion of the charge carriers in semiconductor counters, proportional counters and spark chambers. The material for these two chapters was taken mainly from the literature, although the application of diffusion theory to the calculation of the position resolution in the different detectors was the work of the author. Chapter III includes a general description of the method of charge division on a resistive electrode for obtaining position information from a counter; and the limitations to position linearity and resolution which result from the use of this method (as reported in the literature) are discussed. The electronic system required for a position sensitive proportional counter is described and the design and development by the author of a high precision ratio circuit for this work is outlined. The next chapter is an account of the experimental measurements of resolution and linearity performed by the author on proportional counters which were sensitive to position in one dimension. The position resolutions for single electrons, alpha particles and x-rays were measured, and the experimental resolution for single electrons is compared with the limitations from gas diffusion theory in Chapter V. The data for this comparison was partly drain from the literature; but one of the methods used for calculating the electron diffusion in a gas mixture was devised by the author. The interpretation of the performance of these detectors, in Chapter V, is also that of the writer. Chapter VI deals with the building and operation of a two dimensional position sensitive proportional counter which uses a new method of obtaining the counter signal - from electrodes placed between the anode and the cathode. This method was proposed by Dr. Drever. The counter frame used for this work had been designed initially by him, but a number of important modifications to it were made by the author. The development of the counter and the investigation of its performance were the entire responsibility of the author. The appendix to this thesis is an account of an attempt to observe proportional counter or Oeiger counter operation in a cylindrical detector filled with liquid hexane. This work was initiated and carried out by the writer.