  We present a new evaluation of the far-forward neutrino plus antineutrino
flux and number of events from charm hadron decays in a 400 GeV proton beam
dump experiment like the Search for Hidden Particles (SHiP). Using
next-to-leading order perturbative QCD and a model for intrinsic charm, we
include intrinsic transverse momentum effects and other kinematic angular
corrections. We compare this flux to a far-forward flux evaluated with
next-to-leading order perturbative QCD, without intrinsic transverse momentum,
that used the angular distribution of charm quarks rather than the neutrinos
from their decays. The tau neutrino plus antineutrino number of events in the
perturbative QCD evaluation is reduced by a factor of about three when
intrinsic transverse momentum and the full decay kinematics are included. We
show that intrinsic charm contributions can significantly enhance the number of
events from neutrinos from charm hadron decays. Measurements of the number of
events from tau neutrino plus antineutrino interactions and of the muon charge
asymmetry as a function of energy can be used to constrain intrinsic charm
models.
