  The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is a 26-ton
Gd-doped water Cherenkov detector installed in the Booster Neutrino Beam (BNB)
at Fermilab. The primary physics goal of ANNIE is to study the multiplicity of
final state neutrons from neutrino-nucleus interactions in water. Identifying
and counting final state neutrons provides a new experimental handle to study
systematic uncertainties related to the neutrino energy reconstruction in
oscillation experiments. To achieve that goal ANNIE will make the first use of
the novel Large Area Picosecond PhotoDetectors (LAPPDs). In Phase I, ANNIE
characterised the beam-correlated neutron backgrounds in the detector and
confirmed that they are sufficiently low for the Phase II physics measurements,
anticipated to begin in 2019. In these proceesings the methodology and the
results of Phase I will be discussed.
