THE ARCHITECTURE, DESIGN AND REALISATION OF THE LHC BEAM INTERLOCK SYSTEM

protons per beam, giving a stored energy of around 360 MJ, an unprecedented value for accelerators, enough to heat and melt around 500 kg of copper. An uncontrolled release of the energy stored in LHC beams could lead to serious equipment damage. Major damage of superconducting magnets will result in long repair times as the equipment is delicate and difficult to access. It is therefore vital that the LHC is protected against damage due to uncontrolled beam losses [1, 2]. Protecting equipment against damage in the case of uncontrolled losses is challenging. A nominal injection into the LHC from the CERN Super Proton Synchrotron (SPS) at 450 GeV is already above damage thresholds [3]. The only equipment specifically designed to withstand the full energy of a nominal LHC beam is the LHC Beam Dumping System (LBDS). A Beam Interlock System has been designed for LHC, requesting rapid beam extraction of beam from the LHC by the LBDS in the case of failures or high beam losses being detected by “User Systems” connected to the Beam Interlock System. A dedicated Injection Interlock System ensures that beam from the SPS is only extracted, transferred and injected into the LHC when the conditions are correct. The LHC Beam Interlock System has to inform the Injection Interlock that beam cannot be extracted from SPS when LHC is not ready. This paper discusses the overall architecture, design and realisation of the LHC Beam Interlock System, with particular emphasis on communications and control aspects of the system needed to realise the strict speed and safety requirements.