CMS detector. This drawing by physicist Sergio Cittolin in the style of Leonardo da Vinci, complete with mirror writing, illustrates the outer muon-recording layers of the CMS detector at CERN, the European particle physics laboratory near Geneva. CMS (for Compact Muon Solenoid) is one of four giant detectors which will record subatomic particle interactions at the Large Hadron Collider or LHC proton-proton accelerator due to start operation in 2006-7. Muons are penetrating particles that can travel through all the layers of the detector. (See images A105/204 to A105/209 for other Cittolin 'Leonardo' drawings).