Background Calculations for the High Energy Beam Transport Region of the European Spallation Source

Expected backgrounds in the final accelerator-to-target region
of the European Spallation Source, to be built in Lund,
Sweden, have been calculated using the MCNPX program.
We consider the effects of losses from the beam, both along
the full length and localised at the bending magnets, and
also backsplash from the target. The prompt background is
calculated, and also the residual dose, as a function of time,
arising from activation of the beam components. Activation
of the air is also determined. The model includes the
focussing and rasterising magnets, and shows the effects of
the concrete walls of the tunnel. We give the implications
for the design and operation of the accelerator.