SK-Gd and EGADS: Water Cherenkov evolved

After more than 20 years of operation, Super-Kamiokande will receive a(nother) significant upgrade breathing new life into the venerable experiment. This upgrade will see the addition of gadolinium sulfate to the detector’s ultra-pure water, greatly increasing the detection efficiency for thermal neutrons. This will enable the first observation of the Diffuse Supernova Background (DSNB) whilst improving sensitivity across SK's physics program. The DSNB is the sum of neutrino emissions from all past supernova. Measurement of the DSNB will provide invaluable data for supernova and cosmological models.

While the upgrade offers significant benefits, several technical challenges had to be overcome before implementation. A dedicated R&D facility EGADS (Evaluating Gadolinium’s Action on Detector Systems) was constructed in Kamioka mine to address these challenges. EGADS is a 200 ton, scaled-down SK and has been operating with gadolinium for over 2.5 years. With its R&D mission completed, EGADS is being upgraded to become the world’s most advanced supernova detector capable of immediately and autonomously announcing the arrival of a supernova burst.

This talk will discuss the benefits of SK-Gd, the R&D that has made it possible and the upgrades of the EGADS and SK detectors.