Tune measurement from transverse feedback signals in LHC

Dubouchet, Frederic (CERN, Geneva, Switzerland) ; Höfle, Wolfgang (CERN, Geneva, Switzerland) ; Kotzian, Gerd (CERN, Geneva, Switzerland) ; Levens, T. E. (CERN, Geneva, Switzerland) ; Valuch, Daniel (CERN, Geneva, Switzerland) ; Albuquerque, Paul (School of Engineering, Architecture and Landscape (hepia), HES-SO // University of Applied Sciences Western Switzerland)

We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turnby-turn data using Graphical Processing Units (GPUs). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure, test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.

Type de conférence:
short paper
Ingénierie et Architecture
HEPIA - Genève
inIT - Institut d'Ingénierie Informatique et des Télécommunications
Adresse bibliogr.:
Oxford, UK, 16-19 September 2013
Oxford, UK
16-19 September 2013
4 p.
Publié dans:
Proceedings of International Beam Instrumentation Conference (IBIC 2013), 16-19 September 2013, Oxford, UK
Numérotation (vol. no.):
2013, TUPF29, pp. 579-582
Ressource(s) externe(s):
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 Notice créée le 2020-07-10, modifiée le 2020-10-27

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