Beyond developing and testing individual components, it is important to make critical demonstration tests of cutting-edge subsystems. These are large-scale multi-year endeavors.
The first of these subsystem tests, which has been successfully completed, is the MERcury Intense Target experiment (MERIT) which was hosted at CERN. MERIT demonstrated the proposed proton target technology for Muon Colliders and Neutrino Factories. A free liquid mercury jet was injected into a 15T solenoid, and hit by a suitably intense beam from the CERN Proton Synchrotron. The resulting jet disruption was viewed by high speed cameras. This experiment demonstrated that the technology could be used with very powerful beams, up to about 8MW, a factor of two larger than required for Neutrino Factories and Muon Colliders.
The second systems test, which is currently being prepared, is the Muon Ionization Cooling Experiment (MICE) which is being hosted at the Rutherford-Appleton Lab (RAL) in the U.K. MICE will test a short section of a muon cooling channel in a muon beam, and will hopefully demonstrate that the simulation tools used to design cooling channels correctly describe what happens.