Breaking Taps @breakingtaps.com · Dec 24 1 / 2 The LHCb experiment at CERN's Large Hadron Collider uses HPDs to watch for Cherenkov photons. 9 likes 1 replies ? Reply Replies Breaking Taps · Dec 24 That's all, just thought it was a neat detector! Had never seen these before, always fun to stumble on something new 🙂