Short-baseline electron neutrino disappearance at a neutrino factory

We discuss short-baseline and very-short-baseline v(e) disappearance at a neutrino factory. We take into account geometric effects, such as from averaging over the decay straights, and the uncertainties of the cross sections. We follow an approach similar to reactor experiments with two detectors: we use two sets of near detectors at different distances to cancel systematics. We demonstrate that such a setup is very robust with respect to systematics, and can have excellent sensitivities to the effective mixing angle and squared-mass splitting. In addition, we allow for CPT invariance violation, which can be tested (depending on the parameters) up to a 0.1% level.