17–22 May 2026
C.I.D
Europe/Zurich timezone

Measurement and correction of local chromaticity in the LHC

WEP5071
20 May 2026, 16:00
2h
C.I.D

C.I.D

Deauville, France
Poster Presentation MC5.D02: Nonlinear Single Particle Dynamics Resonances, Tracking, Higher Order, Dynamic Aperture, Code Developments Poster session

Speaker

Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

Description

Local chromaticity can be defined as the local variation of the total betatron phase advance with momentum deviation $\delta$, and it can be interpreted as a measurement of the chromaticity generated over a limited segment of the lattice, rather than for the entire ring. It can be a useful tool to understand various insights of the beam operation, in particular how the phase is locally modulated by $\delta$ and how the overall chromaticity builds up along the lattice. The local chromaticity was first evaluated in the Large Hadron Collider (LHC) during the Run 3 commissioning in 2025, when a large RF frequency scan was performed up to $\pm \, $350 Hz, revealing a very large discrepancy with respect to the LHC optics model. This paper presents the methods and the results of the analysis.

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Author

Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

Co-author

Ewen Maclean (European Organization for Nuclear Research)

Presentation materials

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