Since the beginning of the Large Hadron Collider (LHC) commissioning, spectral components at harmonics of the mains frequency (50 Hz) have been observed in the transverse beam spectrum. This paper presents an overview of the most important observations, collected during the latest physics operation of the LHC in 2018, which clearly indicates that the harmonics are the result of a real beam excitation rather than an instrumental feature. Based on these findings, potential sources of the perturbation are discussed and a correlation with power supply ripple originating from the magnets’ power supplies is presented.

• Received 8 September 2020
• Accepted 18 February 2021

DOI:https://doi.org/10.1103/PhysRevAccelBeams.24.034001

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Published by the American Physical Society