CNGS: effects of possible alignment errors

Simulations of the CNGS neutrino beam from CERN to the Gran Sasso Laboratory (LNGS) assume that the proton beam and all secondary beam elements are perfectly aligned on an axis between the two laboratories. This study examines the effects on the neutrino flux at Gran Sasso of deviations from the axis of the primary proton beam and misalignment of secondary beam elements. It also examines how such deviation or misalignment can be detected at monitors placed along the secondary beam line at CERN and at Gran Sasso. Calculations are based on the CNGS neutrino beam, optimized for appearance experiments as described in the Addendum to the Conceptual Technical Design Report of CNGS. It is shown that the number of neutrino charged current events predicted at Gran Sasso is insensitive to all but the most extreme misalignments.