KARMEN, a detector associated with the ISIS synchrotron at the Rutherford Appleton Laboratory. Neutrinos for study are supplied via the decay of pions produced when a proton beam strikes a target. It operated from 1990 until March 2001, observing the appearance and disappearance of electron neutrinos. KARMEN searched for neutrino oscillations, with implications for the existence of sterile neutrinos.