LHC beam loss monitor system design

At the LHC a beam loss system will be installed for continuous surveillance of particle losses. The system is designed to prevent hardware destructions, to avoid magnet coil quenches and to provide quantitative loss values. Over 3000 ionization chambers will be used to initiate the beam abort if the loss rates exceed the quench levels. The time and beam energy dependent quench levels require the acquisition of chamber currents in the range from 50 pA to 0.5 mA and an update of the values every 89 mu s. The acquisition and control electronics will consist of a front end electronics near (< 400 m) to the ionization chambers and a threshold controller in the surface buildings. The front end will include a charge balance converter, a counter and multiplexer part. The charge balance converter is most suitable to cover the large dynamic range. The introduced error is smaller than few % in the required dynamic range. Six channels will be transmitted over one cable of up to 3 km length. The threshold controller will issue warnings and dump signals depending on the beam energy and the loss durations. (7 refs).