CERN Accelerating science

Preprint
Report number	CERN-ACC-2017-0008
Title	Linear coupling dependence on intensity and a next step towards a feedback (MD1850)
Author(s)	Persson, Tobias Hakan Bjorn (CERN) ; Baud, Guillaume (CERN) ; Coello De Portugal - Martinez Vazquez, Jaime Maria (Universitat Politecnica Catalunya (ES)) ; Gasior, Marek (CERN) ; Giovannozzi, Massimo (CERN) ; Olexa, Jakub (CERN) ; Tomas Garcia, Rogelio (CERN) ; Garcia-Tabares Valdivieso, Ana (Universidad Complutense (ES)) ; Valuch, Daniel (CERN)
Publication	2017
Imprint	28 Feb 2017
Number of pages	11
Subject category	Accelerators and Storage Rings ; Accelerators and Storage Rings
Accelerator/Facility, Experiment	CERN LHC
Keywords	optics ; LHC ; coupling
Abstract	Transverse coupling has proven to be an important variable to control beam dynamics and performance in the LHC. In this report, we present the first measurement of transverse coupling vs beam intensity. The analysis shows no dependency within the experimental uncertainties. This study was made possible with the new implementation of an AC-dipole-like excitation using the ADT. It provides the functionality to excite a single bunch in a train. The demonstration of this functionality is also an important step towards creating an automatic coupling correction tool for the LHC. Transverse coupling has been observed to vary with time at injection. In this report, a quantitative measurement of the coupling as a function of time after ramp-down is presented. Turn-by-turn data was also acquired to compare the performance of the new DOROS system to the standard BPMs.
Submitted by	delphine.rivoiron@cern.ch