Automatic detection of transverse beam instabilities in the Large Hadron Collider

Transverse beam instabilities are a major cause of emittance dilution and beam losses in high intensity hadron accelerators. This paper presents an overview of the system that has been developed for automatic detection of transverse beam instabilities in the Large Hadron Collider at CERN. It relies on the detection of very small transverse beam oscillations using a high sensitivity tune measurement system. These oscillations are then processed online in a field programmable gate array to monitor the growth of any instabilities. When an instability is detected, the acquisition of intrabunch beam position data with a multi-gigahertz bandwidth is triggered. This data allows identification of unstable bunches within bunch trains and provides information on the temporal signature of the instability. The design of these systems and the different algorithms for instability detection that have been tested with beam will be presented along with a detailed description of their performance.