• A. Blas, J.M. Belleman, E. Benedetto, F. Caspers, D.C. Glenat, R. Louwerse, M. Martini, E. Métral, V. Rossi, J.P.H. Sladen
  CERN, Geneva

Since 1999 the PS has been operated without active transverse damping thanks to an increase of the coupling between the transverse planes and the reduction of injection steering errors. Although the LHC requirements are met by these means, a new transverse feedback system has been commissioned to reinforce the robustness of operation and avoid the blow-up generated by residual injection steering errors. This system could also allow the reduction of the chromaticity and reduce the slow incoherent losses during the long PS injection plateau. It could also stabilize the high energy instabilities that appear occasionally with the LHC nominal beam and may be a limiting factor for ultimate LHC beam. Highlights include a signal processing with an automatic delay adapting itself to the varying revolution frequency, a programmable betatron phase adjustment along the cycle, pick-ups that have been re-furbished with electronics covering the very low frequency of the first betatron line and a compact wideband high-power solid state amplifier that drives the strip-line kicker via an impedance matching transformer. The overall system is described together with experimental results.

• V. Rossi
  CERN, Geneva

In the framework of the LHC project the concept has been developed of a global digital signal processing unit (DSPU) that implements in numerical form the architecture of low-level RF systems [1]. The approach, using an FPGA as core for the low-level system, is very flexible and allows the upgrade of the signal processing by modification of the original firmware [2]. The achieved performances of the LHC 1-Turn delay Feedback are compared with project requirements. The PS Transverse Damper DSPU, with automatic loop delay compensation adapting to the beam’s time of flight and Hilbert Filter for single pick-up betatron phase adjustment, is presented. A modified DSPU with digital inputs for the LHC Transverse Damper is also presented.

[1] V. Rossi, CERN SL-2002-047-HRF, CERN, Geneva, July 2002.
[2] V. Rossi, CERN BE-2009-009, CERN, Geneva, January 2009.

• A.C. Butterworth, M. E. Angoletta, L. Arnaudon, P. Baudrenghien, J. Bento, T. Bohl, O. Brunner, E. Ciapala, F. Dubouchet, G. Hagmann, W. Höfle, T.P.R. Linnecar, P. Maesen, J.C. Molendijk, E. Montesinos, J. Noirjean, A.V. Pashnin, V. Rossi, J. Sanchez-Quesada, M. Schokker, E.N. Shaposhnikova, D. Stellfeld, J. Tuckmantel, D. Valuch, U. Wehrle, F. Weierud
  CERN, Geneva
• R. Sorokoletov
  JINR, Dubna, Moscow Region

Hardware commissioning of the LHC RF system was successfully completed in time for first beams in LHC in September 2008. All cavities ware conditioned to nominal field, power systems tested and all Low level synchronization systems, cavity controllers and beam control electronics were tested and calibrated. Beam was successfully captured in ring 2, cavities phased, and a number of initial measurements made. These results are presented and tests and preparation for colliding beams in 2009 are outlined.