  The invention of self-shielding copper substrate neutron guides is described,
along with the rationale behind the development, and the realisation of
commercial supply. The relative advantages with respect to existing
technologies are quantified. These include ease of manufacture, long lifetime,
increased thermal conductivity, and enhanced fast neutron attenuation in the
keV-MeV energy range. Whilst the activation of copper is initially higher than
for other material options, for the full energy spectrum, many of the isotopes
are short-lived, so that for realistic maintenance access times the radiation
dose to workers is expected to be lower than steel and in the lowest zoning
category for radiation safety outside the spallation target monolith. There is
no impact on neutron reflectivity performance relative to established
alternatives, and the manufacturing cost is similar to other polished metal
substrates.
