Using a Ring Imaging Cherenkov (RICH) detector

I'm not clear on how RICH (Ring Imaging Cherenkov) detectors identify particles, as much as I've tried to read up on it. So they measure the angle Cherenkov light is emitted at, which is related to the refractive index of the material, speed of light and the speed of the particle. How can that be used for particle ID? And why are these detectors particularly good at differentiating between pions and kaons?

I realise this seems like a question that should be easily solved by googling, but I'm not having any luck there!

• Expanding the acronym: Ring Imaging Cherenkov. – user137289 Dec 6 '16 at 21:58