Impact of the muon beam divergence and polarization on the prediction accuracy of the neutrino flux at a distant detector of a neutrino factory

The neutrino spectra at a detector located 3500 km from a neutrino factory have been calculated for a range of the muon beam divergence and polarization values. It is shown that the neutrino event rates can be predicted with an accuracy of approx 0.8%, provided that the muon beam divergence is of order 0.1/gamma submu and known at a 10% level. The polarization of the muon beam does not contribute to the event rate uncertainty if it is known better than 0.5%.