Constraining the Diffuse Supernova Neutrino Background with SK-Gd

The main aim of the research programme will be enhancing the capability of existing and future water Cerenkov detectors (in particular the existing Super Kamiokande experiment and the planned Hyper Kamiokande experiment). There are two principle themes of the research. The first is a hardware/software project to develop a variant of existing photodetectors proposed by Oxford and the Rutherford Lab. These new photodetectors will consist of photomultipliers with attached wavelength shifting plastic plates. This is a technique already used in the field, but the new proposal is to alter the geometry of the WS plates to optimize the timing response of the resulting system. We believe this will produce a cheaper alternative to existing photomultiplier options that could be used to enhance the low-energy physics of the Hyper Kamiokande experiment. The project will consist of designing, building, and testing the first working prototypes of these new detectors. The main aim is to demonstrate that a cost-effective device can be built with high enough photon detection efficiency and good timing. This will be done in collaboration with a number of UK and foreign universities, and a possible outgrowth would be to develop a new type of wavelength-shifting plastic (because the existing alternatives seem unnecessarily expensive) which could be licensed to a UK firm to produce. The second theme of the research project will be to use the newly added neutron-detection capability of Super Kamiokande to improve the physics sensitivity to oscillations or proton decay (enhanced neutron-detection capability will help both by suppressing background in proton decay searches and by enabling statistical separation of neutrino from anti-neutrino events in oscillation searches). This will be primarily a software analysis task, also performed in collaboration with other university groups.