  MAST-U has recently started operating with a Super-X divertor, designed to
increase total flux expansion and neutral trapping, both predicted through
simple analytic models and SOLPS calculations to reduce the plasma and impurity
density detachment thresholds. In this study, utilising the SOLPS-ITER code, we
are quantifying the possible gain allowed by the MAST-U Super-X and neutral
baffling geometry, in terms of access to detachment. We show that a significant
reduction of the upstream density detachment threshold (up to a factor 1.6)
could be achieved in MAST-U, for the Super-X, as opposed to conventional
divertor geometry, mainly through an increased total flux expansion, neutral
trapping being found very similar between the different configurations. We also
show that variations of the strike-point angle are complex to interpret in such
a tightly baffled geometry, and that a case in which the target normal points
more towards the separatrix does not necessarily imply a lower detachment
threshold. As in previous calculations for TCV, we quantify the role of neutral
effects through developing and applying a quantitative definition of neutral
trapping.
