Ion Chamber Arrays for the NuMI Beam at Fermilab

The Neutrinos at the Main Injector (NuMI) beamline will deliver an intense ν
μ
beam by focusing a beam of mesons into a long evacuated decay volume. We have built 4 arrays of ionization chambers to monitor the ν beam direction and quality. The arrays are located at 4 stations downstream of the decay volume, and measure the remnant hadron beam and tertiary muons produced along with neutrinos in meson decays.