ANNIE: Phase I Results and Phase II Status

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is a water Cherenkov detector located on the Booster Neutrino Beam at Fermilab. ANNIE was built in 2016 and Phase I of the experiment was completed in November 2017. During Phase I, ANNIE successfully measured the beam-induced background neutron flux at different locations in the water volume. The ANNIE detector is currently undergoing the upgrade to the Phase II configuration. The main goal of Phase II is measuring the final state neutron multiplicity from charged current neutrino-nucleus interactions within the gadolinium-loaded water. The upgrade work includes testing the Muon Range Detector, increasing the photocathode coverage in the tank, installing Large Area Picosecond Photodetectors (LAPPDs) and adding gadolinium. In this talk, we present the physics results of Phase I, the characterization test results of LAPPDs and the current status of Phase II.