Bunched-beam Schottky monitoring in the LHC

The LHC Schottky beam diagnostic system has the potential to measure beam parameters such as tune, chromaticity and momentum spread in a non-invasive way. It does so by detecting beam induced signals at 4.8 GHz, and extracting the characteristic modulation caused by incoherent motion of particles within a bunch. The system was commissioned in 2011 and provided satisfactory beam-parameter measurements during LHC Run I for lead-ions. However, for protons its usability was substantially limited due to strong interfering common-mode signals. The system was upgraded with optimized traveling-wave pick-ups and an improved microwave signal path. Design and operational aspects for the complete system are shown, and the results from measurements with LHC beams in Run II are presented and discussed.