A BLM system for the LHC ring

Most beam losses in LHC will be concentrated in the cleaning sections and the remaining halo will be spread around the whole ring with a high probability of hitting the vacuum chamber within or near the quadrupoles where the beam envelope goes through a maximum. The position and sensitivity of six beam loss detectors per quadrupole has been computed recently [2]. The thresholds of lost protons to induce a quench in quadrupoles or dipoles are shown and a proposal is made for a survey of intermediate losses, every 10 ms and continuous losses measured over 4 s. In each lattice cell there will be a local computer for communication which could survey the beam losses and give alarms, and display the time evolution of losses over 1 s or over a full day.