The distinct pattern produced by Čerenkov radiation allows for particle identification, an important tool both understanding the potential proton decay signal and for rejecting backgrounds. The ID is possible because the sharpness of the edge of the ring depends on the particle producing the radiation. Electrons (and therefore also gamma rays) produce fuzzy rings due to the multiple scattering of the low mass electrons. Minimum ionizing muons, in contrast produce very sharp rings as their heavier mass allows them to propagate directly.