  Hadron scattering and production uncertainties are a limiting systematic on
accelerator and at-mospheric neutrino flux predictions. New hadron measurements
are necessary for neutrino fluxpredictions with well-understood and reduced
uncertainties. We propose a new compact experimentto measure hadron scattering
and production cross sections at beam energies that are inaccessibleto
currently operating experiments. These measurements can reduce the current 10%
neutrino fluxuncertainties by an approximate factor of two.
