Detecting Failures in Electrical Circuits Leading to Very Fast Beams Losses in the LHC

Failures in the powering of LHC magnets could lead to very fast beam losses at collimators, possibly within less than 10 turns. Beam loss monitors would normally detect such losses and trigger a beam dump. However, the available time for detection with these monitors before reaching the damage level of a collimator might not be sufficient, in particular for beams with few particles in the tail of the transverse particle distribution. This has always been of concern and becomes even more relevant since very fast losses have been observed recently at HERA. In this paper, we present particle tracking studies for the LHC to identify failures of critical magnets in the accelerator. We propose a fast detection of such failures in the electrical circuit, either with highly precise hall probes for current measurement or measurements of the induced inductive voltage during the current decay. Where active detection is not possible, additional inductance in series with the electrical circuit can relax the time constraints for a safe detection of the failure.