In March, the Eos collaboration hit a major milestone in their development of a novel “hybrid” neutrino detector which simultaneously leverages both Cherenkov and scintillation signatures.
Eos is a 3.5-meter tall, 3-meter wide cylinder, ultimately to be filled with water and an organic scintillator surrounded by highly sensitive Photomultiplier Tubes (PMTs). By combining Cherenkov and scintillation emission the detector has the potential to provide greater sensitivity and resolution than conventional detectors. These improvements could be a game-changer for future neutrino physics experiments while also providing new capabilities for nuclear non-proliferation.
On the 8th March 2024 the detector saw its first light. By injecting blue LED flashes into Eos using its light injection calibration system, the PMTs were able to observe pulses in the single photon regime. This moment represented the culmination of effort from the entire collaboration, demonstrating the integration of many critical subcomponents of this next-generation neutrino detector.
This event proved to be ideally timed, with the results coming just weeks before the Eos Collaboration Meeting which ran from the 21st to 22nd March allowing the results of this landmark to be presented to the entire team. The observation indicates that the detector is functioning as expected, and will now imminently move into the next stage of its development – filling with water.
The water fill will provide an essential period for the Eos team to fully understand the detector performance, test its modeling, and scrutinize its reconstruction techniques through the deployment of an array of calibration sources. At this point, the team will be ready to inject Water based Liquid Scintillator into Eos’ central acrylic volume. Through the further deployment of radioactive sources, the Eos collaboration will be able to fully understand this novel neutrino detection medium. Eos aims to demonstrate the capabilities that the latest fast photosensors, combined with high photocathode coverage, and the use of dichroicons in spectral photon sorting will have in separating Cherenkov and scintillation emission from WbLS. In doing this, Eos hopes to illustrate the advantages of this “hybrid” detection for many future neutrino applications. This will be an exciting moment: Eos’ performance this year can demonstrate a bright future for these novel techniques. The scope of possibilities are vast, from using Eos itself in nuclear nonproliferation experimentation to scaling up the technology to experiments such as the proposed Theia to apply these techniques in the search for the fundamental nature of neutrinos.
The Eos collaboration is led by NSD Faculty Scientist Gabriel Orebi Gann.
Figure 1: Preliminary Eos event display of a commissioning run. Here light was injected between columns 16 and 17 of the side PMTs. The resulting detected light can clearly be seen by the PMT array on the opposite side of the detector.