Speaker
Description
Hyper-Kamiokande is a state-of-the-art water Cherenkov neutrino detector, currently under construction in Japan. In its capacity as the far detector within a long baseline program, Hyper-K aims to make high precision measurements of key neutrino oscillation parameters and has the ability to observe exotic phenomena such as proton decay and other BSM physics. One of the main backgrounds to such studies come from cosmic ray muons. To veto these muons, an outer detector region is instrumented with 3600 PMTs with wavelength shifters and the whole region is outfitted with a highly reflective material known as Tyvek to maximise light collection. This talk presents the measurement programme developed to measure the reflectivity of various Tyvek material samples in both air and water to inform the selection of final products for Hyper-K OD.