Author: Levens, T.E.
Paper Title Page
MOPC35 A Beam-Synchronous Gated Peak-Detector for the LHC Beam Observation System 147
  • T.E. Levens, T. Bohl, U. Wehrle
    CERN, Geneva, Switzerland
  Measurements of the bunch peak amplitude using the longitudinal wideband wall-current monitor are a vital tool used in the Large Hadron Collider (LHC) beam observation system. These peak-detected measurements can be used to diagnose bunch shape oscillations, for example coherent quadrupole oscillations, that occur at injection and during beam manipulations. Peak-detected Schottky diagnostics can also be used to obtain the synchrotron frequency distribution and other parameters from a bunched beam under stable conditions. For the LHC a beam-synchronous gated peak detector has been developed to allow individual bunches to be monitored without the influence of other bunches circulating in the machine. The requirement for the observation of both low intensity pilot bunches and high intensity bunches for physics requires a detector front-end with a high bandwidth and a large dynamic range while the usage for Schottky measurements requires low noise electronics. This paper will present the design of this detector system as well as initial results obtained during the 2012-2013 LHC run.  
poster icon Poster MOPC35 [2.792 MB]  
TUPF28 A Leading-Edge Hardware Family for Diagnostics Applications and Low-Level RF in CERN’s ELENA Ring 575
  • M.E. Angoletta, A. Blas, M. Jaussi, P.M. Leinonen, T.E. Levens, J.C. Molendijk, J. Sanchez-Quesada, J. Simonin
    CERN, Geneva, Switzerland
  The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons transferred from the CERN’s Antiproton Decelerator (AD). The requirements for the acquisition and treatment of signals for longitudinal diagnostics are very demanding, owing to the revolution frequency swing as well as to the digital signal processing required. The requirements for the Low-Level RF (LLRF) system are very demanding as well, especially in terms of revolution frequency swing, dynamic range and low noise required by the cavity voltage control and digital signal processing to be performed. Both sets of requirements will be satisfied by using a leading-edge hardware family, developed to cover the LLRF needs of all synchrotrons in the Meyrin site; it will be first deployed in 2014 in the CERN’s PSB and in the medical machine MedAustron. This paper gives an overview of the main building blocks of the hardware family and of the associated firmware and IP cores. The performance of some blocks will also be detailed.  
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]