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Internal Note
Report number CERN-ACC-NOTE-2018-0017
Title MD 2197: Experimental studies of Landau damping by means of Beam Transfer Function measurements in the presence of beam-beam interactions and diffusive mechanisms
Author(s) Tambasco, Claudia (EPFL - Ecole Polytechnique Federale Lausanne (CH)) ; Barros Marin, Manoel (CERN) ; Barranco Garcia, Javier (EPFL - Ecole Polytechnique Federale Lausanne (CH)) ; Boccardi, Andrea (CERN) ; Buffat, Xavier (CERN) ; Bruce, Roderik (CERN) ; Gasior, Marek (CERN) ; Hostettler, Michi (Universitaet Bern (CH)) ; Lefevre, Thibaut (CERN) ; Louro Alves, Diogo Miguel (CERN) Visa alla 16 författare
Corporate author(s) CERN. Geneva. ATS Department
Publication 2018
Imprint 23 Feb 2018
Number of pages 8
Subject category Accelerators and Storage Rings
Accelerator/Facility, Experiment CERN LHC
Keywords Accelerator Physics ; Beam-beam effects ; Beam instabilities ; Beam Transfer Function ; Stability diagram
Abstract Beam Transfer Function (BTF) measurements are direct measurement of the stability diagrams that define the stability threshold of coherent beam instabilities driven by the impedance. At the LHC, some coherent instabilities at flat top energy are still not fully understood and the BTF measurements provide a method to experimentally probe the Landau damping of the proton beams. The BTF response is sensitive to the particle distribution changes and contain information about the transverse tune spread in the beams. The BTF system has been installed in the LHC in the 2015 in order to investigate the Landau damping at different stages of the operational cycle, machine configurations (different octupole currents, crossing angles, tunes etc...) and in presence of beam-beam excited resonances that may provoke diffusion mechanisms with a consequence change of Landau damping. Past MDs showed some difficulties for the reconstruction of the stability diagram from BTF measurements and several improvements on the BTF system have been put in place in order to improve the signal to noise ratio. In this note a detailed procedure of the MD is described together with some preliminary results of BTF measurements in the presence of linear coupling.
Submitted by alessia.valenza@cern.ch

 


 Journalen skapades 2018-02-27, och modifierades senast 2018-03-06


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