Author: Kotzian, G.
Paper Title Page
TUPF29 Tune Measurement from Transverse Feedback Signals in LHC 579
  • F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch
    CERN, Geneva, Switzerland
  • P. Albuquerque
    HES-SO//Geneva, Geneva, 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, turn-by-turn data using Graphical Processing Units (GPU). 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.  
poster icon Poster TUPF29 [1.052 MB]  
WEPC12 Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System 690
  • G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle
    CERN, Geneva, Switzerland
  The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.