Organisation: JGU > Faculty 08 > Institute of Physics > Experimental Particle & Astroparticle Physics (ETAP) > ANNIE
Research: JGU > Faculty 08 > Physics > Astroparticle & Neutrino Physics > ANNIE
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.
Beyond its physics program, ANNIE acts as a testbed for novel detector technologies:
1. Enhanced Neutron Detection with Gadolinium-Doped Water
The ANNIE experiment employs gadolinium-doped water as its neutrino interaction medium, significantly improving neutron capture efficiency compared to conventional Water Cherenkov detectors. This capability is essential for accurately determining the number of neutrons produced in neutrino interactions.
2. Advanced Timing and Position Reconstruction Using LAPPDs
To achieve superior vertex and track reconstruction, ANNIE integrates Large Area Picosecond Photodetectors (LAPPDs). These devices provide single-photon timing at the picosecond scale and sub-centimeter spatial resolution within a 20 cm × 20 cm active area. As of early 2024, ANNIE is collecting data with three fully operational LAPPDs installed in the water tank.
3. First Neutrino Detection in Water-Based Liquid Scintillator
In 2023, ANNIE achieved the first observation of neutrino interactions in Water-based Liquid Scintillator (WbLS), a novel detection medium. WbLS produces both Cherenkov light and a faint scintillation signal, enhancing sensitivity to low-energy particles below the Cherenkov threshold. Initial results from a test deployment of 365 kg of WbLS in a transparent acrylic vessel inside the ANNIE tank have been published.
Based on the successful first deployment of WbLS in ANNIE, the collaboration is now moving towards the installation of a larger WbLS volume in the ANNIE water tank. The goal is the demonstration of the full event reconstruction capability in an extended WbLS volume in combination with an array of ultra-fast LAPPDs. For this, the Mainz group is developing a transparent Nylon Vessel that will separate the inside WbLS from the outside water in contact with the detector materials. This vessel will fill the entire active volume of the ANNIE water tank and contain 8 tons of WbLS. Moreover, we are developing novel reconstruction techniques to identify the scintillation light of recoil protons in neutrino interactions, exploring the potential to improve the energy resolution for the incident neutrinos. Both will be important ingredients in the preparation of a future large scale neutrino experiment based on the new technology.
In fall 2024, we visited the US-state Iowa, where the Annie Experiment is located. We were excited to insert the SANDI vessel filled with gadolinium-loaded WbLS for the second time – and celebrated the successful deployment.