A detailed study of drift chambers

Abstract

This thesis describes a study made at Durham University of a new type of particle detector, the drift chamber. The device is a development of the multiwire proportional chamber but has a superior spatial resolution and requires less electronic channels per detecting area. Two types of drift chamber have been built for investigating various operating characteristics, and the specific design and constructional details of each is described. The main part of the work deals with an investigation into the behaviour of a specific gas mixture, argon + 10% methane, with regard to its suitability for drift chamber application. Measurements have been made of output pulses, detection efficiency, spatial resolution and electron drift velocity, and their variation with operating conditions, including the angle of the particle trajectory to the chamber normal. Particular emphasis has been placed on the behaviour of chambers in strong magnetic fields, as this represents a common practical operating condition. Test chambers with this gas mixture have been successfully operated using a simple compensation technique, on an accelerator beam at Daresbury Laboratories, at magnetic fields up to 13.5kG. Comparisons with other gas mixtures are made, using data obtained during this work and the experimental and theoretical results of other workers. The results have indicated that argon + 10% methane is entirely applicable to practical drift chamber use and its behaviour is well described by simple theories. As an example of a practical application, the design, construction and testing of a third type of chamber for use in a high energy physics experiment involving non-uniform magnetic fields, is described.