The LHCb wire chamber

LHCb measures muons using gold plated tungsten wires stretched over read-out pads. A high voltage is applied across the wires and pads and the set-up is bathed in a gas mixture. Passing muons interact with the gas, knocking out electrons from its atoms in a process called ionization. Both the ionized atoms and the electrons then drift in the electric field. This movement creates an electric signal in the wires and pads that is used to identify where the muon has passed. In total, the LHCb muon detectors contain about 2 million wires and are capable of making measurements 40 million times a second – every time the particle beams collide.