Design of a high resolution time-of-flight crystal analyser spectrometer and hydrogen diffusion in intermetallic compounds
The main part of this thesis concerns the design and simulation of a polarization analysis backscattering cold neutron spectrometer, OSIRIS, at the ISIS pulsed neutron source. The OSIRIS instrument consists of two parts, a high-resolution powder diffractometer and a micro-eV resolution inelastic spectrometer. The incident cold neutron beam has the option of being polarised by means of a series of interchangeable polarising benders. The inelastic spectrometer consists of an analyser array constructed from pyrolytic graphite crystals situated in nearbackscattering geometry. Monte Carlo simulations have been performed in order to optimise and investigate various components of the spectrometer, including the guide, polarisers and analyser. A microguide testing device, MITED, has been constructed, commissioned and, using it, measurements have been made on neutron guide sections. This instrument has also been used to test the reflectivity of supermirror coated guide sections. Originally, it was the aim of this thesis to carry out all the scientific commissioning experiments required for OSIRIS. This has become unfeasible due to manpower problems within the ISIS facility, which have delayed the construction of the OSIRIS spectrometer and have moved it out of the time range of this thesis. Therefore an extra section of work has been included, on a family of intermetallic metal hydride systems that it will be of interest to investigate using the OSIRIS instrument. A general study of the diffusion of hydrogen in C15 Laves phase intermetallic compounds has been performed. This has employed the techniques of quasielastic neutron scattering, inelastic vibrational spectroscopy, diffraction and muon spectroscopy.