  Liquid Argon Time Projection Chambers (LArTPCs) are ideal detectors for
precision neutrino physics. These detectors, when located deep underground, can
also be used for measurements of proton decay, and astrophysical neutrinos. The
technology must be completely developed, up to very large mass scales, and
fully mastered to construct and operate these detectors for this physics
program. As part of an integrated plan of developing these detectors, accurate
measurements in LArTPC of known particle species in the relevant energy ranges
are now deemed as necessary. The LArIAT program aims to directly achieve these
goals by deploying LArTPC detectors in a dedicated calibration test beam line
at Fermilab. The set of measurements envisaged here are significant for both
the short-baseline (SBN) and long-baseline (LBN) neutrino oscillation programs
in the US, starting with MicroBooNE in the near term and with the adjoint near
and far liquid argon detectors in the Booster beam line at Fermilab envisioned
in the mid-term, and moving towards deep underground physics such as with the
long-baseline neutrino facility (LBNF) in the longer term.
