• K.B. Scheidt, F. Epaud
  ESRF, Grenoble

The ESRF Storage Ring has, in the period of the last 3 winter months, been fully equiped with new electronics for its BPM system while causing a minimum disturbance to its large community of X-ray beam-line users. The Libera-Brillance is now actively doing the treatment of the weak RF signals on all of the 224 BPM stations, and has replaced the old RF-Multiplexing system that had served reliably for nearly 17 years. This paper will describe the precautions that had been taken to make the whole transition as smooth and fluid as possible, with regards to both the reliability for the SR operation and the positional stability of the X-ray beams for the users of more than 40 beamlines. Information will be given on the structure of the network and computer control, based on the Tango distributed control system and its associated device-servers and tools. Results obtained will be presented to demonstrate the strongly improved performance and functionality in every field of application, and that will make this new BPM system the key component in the near future’s upgraded orbit stabilization system.

• M. Tobiyama, J.W. Flanagan, T.M. Mitsuhashi, T. Obina, M. Tadano, R. Takai
  KEK, Ibaraki

A transverse bunch by bunch feedback system using iGp feedback processors has been tested at the KEK-PF. The system consists of a bunch position detection system using 1.5 GHz components of the beam (3 x fRF), iGp feedback signal processors, and a transverse feedback kicker with a high power amplifier. It shows sufficient performance to suppress instabilities completely up to a beam current of 450mA. Results of the mode analysis of the instabilities using the grow-damp function of the iGp are also shown.

• R. de Maria
  BNL, Upton, Long Island, New York
• J.D. Fox
  SLAC, Menlo Park, California
• W. Höfle, G. Kotzian, G. Rumolo, B. Salvant, U. Wehrle
  CERN, Geneva

We present the performance and limitations of the SPS exponential coupler for transverse instability measurements with LHC type beam. Data were acquired in 2008 in the SPS in the time domain with a bandwidth of up to 2.5 GHz. The data were filtered to extract the time evolution of transverse oscillations within the less than 5ns long LHC type bunches. We describe the data filtering techniques and reveal the limitations of the pick-up due propagating modes.

• F. Falkenstern, F. Hoffmann, J. Kuszynski
  BESSY GmbH, Berlin
• P. Kuske
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin

BunchView is a system for the direct measurement of the current from each bunch circulating in a storage ring based on the analysis of the RF-signals delivered by a set of striplines. This paper describes the development, achievements, operation, and results of this fast and accurate bunch current monitor built for the BESSY and MLS storage rings. Using a combination of a 14/16Bit ADC, a high-speed FIFO, ECL technique, and FPGAs, a real-time measurement of the fill-pattern with high accuracy and bunch-by-bunch resolution was achieved. The results are identical to the fill-pattern determined by time correlated single photon counting based on synchrotron radiation detected with an avalanche photo diode. BunchView is fully integrated into the EPICS control system. The data provided by the BunchView monitor give accurate bucket position in the ring and bunch current over a wide range of currents. The smallest measured single bunch current is less than 100nA. In the future the system will be used in the top-up mode of operation in order to inject beam into the emptiest buckets and thus keep the fill-pattern stable over longer periods of time.

• G. Rehm, I.P.S. Martin, A.F.D. Morgan
  Diamond, Oxfordshire
• R. Bartolini, V. Karataev
  JAI, Oxford

The operation of the Diamond storage ring with short electron bunches using ‘low alpha’ optics for generation of Coherent THz radiation and short X-ray pulses for time-resolved experiments is limited by the onset of microbunch instabilities. We have installed two ultra-fast (time response is about 250 ps) Schottky Barrier Diode Detectors sensitive to radiation within the 3.33-5 mm and 6-9 mm wavelength ranges. Bursts of synchrotron radiation at these wavelengths have been observed to appear periodically above certain thresholds of stored current per bunch. The fast response allows a bunch-by-bunch and turn-by-turn detection of the burst signal, which facilitates study of the bursts’ structure and evolution. In this paper we present our first results for various settings of alpha and also discuss future plans for the modification of a beam port to improve sensitivity of the system.