The upgrade consisted of the removal of one of the two gadolinium poisoning foils in the water moderator, so that beamlines on the south side (MAPS, SXD and VESUVIO) benefit from a factor of up to two increase in thermal neutron flux [see accompanying plot]. Beamlines on the north side (POLARIS, TOSCA and INES) remain completely unchanged, in particular with no modification to their wavelength / energy resolution. The neutron flux and resolution profiles measured after the upgrade were in excellent agreement with simulations performed beforehand by the ISIS neutronics group, and thus provide a useful additional benchmark for the TS-1 upgrade project.
The benefits of the extra flux for the south side instruments include the ability to measure smaller samples (SXD), improve diffraction data collection done in parallel with spectroscopy experiments (VESUVIO), and improve the speed and statistical quality of low energy excitations measurements (MAPS).
