NuMI Beam Flux Inferred from fitting ND Data

A knowledge of the production of secondary hadrons off the NuMI target is needed to accurately predict the neutrino flux in the MINOS experiment. A method for tuning the underlying production spectra of secondary hadrons to match the MINOS near detector data will be described. The NuMI beam has the advantage of tuning the typical beam energy by changing the target configuration. Hadron production and the NuMI beam flux are constrained by a fit to data taken in multiple beam configurations. Preliminary results will be shown.