The Accelerator Neutrino Neutron Interaction Experiment

ANNIE is a gadolinium-doped water Cherenkov detector performing measurements in the Booster Neutrino Beam (BNB) at Fermilab in Batavia (Illinois) in the United States. The primary goal is the determination of the neutron multiplicity generated by muon neutrino interactions in water as a function of the momentum transfer: The results will impact the reconstruction of neutrino interactions in long-baseline oscillation experiments but also the search for proton decay and the Diffuse Supernova Neutrino Background in future large-scale detector.
The use of gadolinium-doped water as neutrino target in ANNIE greatly enhances the neutron detection efficiency compared to a normal Water Cherenkov detectors and is vital for a precise measurement of the final neutron number. Furthermore, the experiment utilizes state-of-the-art technology to enhance its vertex and track reconstruction capabilities: Large Area Picosend Photodetectors (LAPPDs) allow the reconstruction of picosecond-timing of single photons whilst simultaneously allowing for sub-cm position resolution within the 20cm x 20cm detection area.
ANNIE has entered its physics phase (Phase II) in early 2021. Since March 2022, the first LAPPD has been successfully deployed, with the installation of four further ones to follow before the end of the year.

Inside view of the ANNIE water tank, schematic view of the experimental setup, first LAPPD deployed in ANNIE (with waterproof housing)

Mainz: Event reconstruction and preparation of Phase-III

For ANNIE Phase II, the involvement of the Mainz group focuses on the development of reconstruction algorithms and monitoring software for ANNIE Phase II. In parallel, we are conducting preparative studies for a detector upgrade in which an acrylic vessel (SANDI) containing Water-based Liquid Scintillator (WbLS) will be placed in the center of the ANNIE water volume. This new scintillator technology provides the unique possibility of detecting Cherenkov light and scintillation light at the same time, which will be of special interest for rare event searches such as proton decay and the detection of the Diffuse Supernova Background (DSNB) in future kiloton-scale WbLS detectors. The successful implementation of WbLS in ANNIE will thus serve as an important benchmark for future planned neutrino Long Baseline projects such as THEIA. In parallel, the Mainz group is performing laboratory measurements for the characterization of WbLS properties, with two specialized setups to study the propagation and light yield of scintillation and Cherenkov light.

the SANDI acrylic vessel to hold water-based liquid scintillator (WbLS), WbLS samples produced in Mainz, the SCHLYP setup for separate measurement of Cherenkov and scintillation light yields

Please contact Prof. Dr. Michael Wurm for Bachelor, Master and PhD theses.