• M. Wendt, C.I. Briegel, N. Eddy, B.J. Fellenz, E. Gianfelice-Wendt, P.S. Prieto, R. Rechenmacher, D.C. Voy
  Fermilab, Batavia
• N. Terunuma, J. Urakawa
  KEK, Ibaraki

To achieve a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring, the BPM read-out system is currently upgraded with new high resolution electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducable beam position readings. The concept and its technical realization, as well as preliminary beam study results are presented.

• E. Adli
  University of Oslo, Oslo
• R. Corsini, S. Döbert, A. Dubrovsky, G. Riddone, D. Schulte, I. Syratchev
  CERN, Geneva
• R.J.M.Y. Ruber, V.G. Ziemann
  Uppsala University, Uppsala
• S. Vilalte
  IN2P3-LAPP, Annecy-le-Vieux

The two-beam acceleration scheme foreseen for CLIC and the associated radio-frequency (RF) components will be tested in the Two-beam Test Stand (TBTS) at CTF3, CERN. Of special interest is the performance of the power extraction structures (PETS) and the acceleration structures as well as the stability of the beams in the respective structures. After the recent completion of the TBTS, the first 12 GHz PETS has been tested with beam. Up to 30MW of RF power was extracted from a 5A electron beam, using so called recirculation of the RF power inside the PETS. The TBTS instrumentation, including inductive beam position monitors, allows precise measurement of beam parameters before and after the PETS as well as RF power and phase. Measurements of transverse kicks, energy loss and RF power with recirculation are discussed and compared with estimations, including first measurements of RF pulse shortening probably due to break down.

• D. B. Belohrad, O.R. Jones, M. Ludwig, J.-J. Savioz, S. Thoulet
  CERN, Geneva

The fast beam intensity measurements for the LHC are provided by eight Fast Beam Current Transformers (FBCT). Four FBCTs installed in the LHC rings are capable of providing both bunch-by-bunch and total turn-by-turn beam intensity information. A further four FBCTs, two in each of the LHC dump lines, are used to measure the total extracted beam intensity. In addition to providing intensity information the ring FBCTs also send signals to the machine protection system. This increases the complexity of both the RF front-end and the digital acquisition parts of the signal processing chain. The aim of this paper is to discuss the implemented hardware solution for the FBCT system, in particular with respect to the signal distribution, FPGA signal processing, calibration, and interaction of the FBCTs with the machine protection chain.

• M. Putignano, K.-U. Kühnel
  MPI-K, Heidelberg
• M. Putignano, C.P. Welsch
  The University of Liverpool, Liverpool

Growing interest in the development of low energy projectile beams, in particular heavy ions and antiprotons, calls for new beam instrumentation to be developed to match the strict requirements on ultra-high vacuum and low beam perturbation. When it comes to transverse profile monitoring, a convenient solution for simultaneous determination of both transverse profiles is found in a neutral supersonic gas-jet target shaped into a thin curtain and the two-dimensional imaging of the gas ions created by impacting projectiles. The resolution and vacuum efficiency of this monitor is directly linked to the characteristics of the gas-jet curtain. In this contribution we describe the design of a nozzle-skimmer system to be used for the creation of the jet curtain in the first prototype of such a monitor. Using numerical fluid dynamics simulations, we present the effects resulting directly from changes in the geometry of the nozzle-skimmer system on the characteristics of the jet curtain.

• R.S. Mao, Z.G. Hu, B. Tang, J.X. Wu, J.W. Xia, G.Q. Xiao, H.S. Xu, Z.G. Xu, Y.J. Yuan, T.C. Zhao, J.H. Zheng
  IMP, Lanzhou

This paper gives the detectors used for slowly extracted heavy ions from CSR. The beam profiles are measured with viewing screens and anode-striped ion-chambers. The currents are determined with scintillators and ion-chambers. The signal processing system and the measurement results are also presented.

• S. Hunziker, V. Schlott
  PSI, Villigen

The PSI 250 MeV Injector, a precursor to the SwissFEL with its extreme jitter and stability demands poses new challenges for the synchronization system. Our concept is double-tracked: low risk electrical and best potential performance and flexibility optical. The electrical distribution system, being established first, relies on reliable technology. Optimized to achieve a benchmark jitter performance of around 10fs and a long term drift stability of some 10fs in the most critical parts of the machine it will also backup the optical system. Sub 10fs jitter and drift figures are being aspired for the latter. In this contribution, both systems are presented, measurements of electrical and optical reference signal jitter and long term cable and coupler drifts will be shown. A cable temperature stabilization system and the influence of mechanical noise will be discussed, too. Finally, first jitter measurements of the optical system will be presented.

• 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.

• H.W. Mostert, J.L. Conradie, M.A. Crombie, J.G. De Villiers, K. Springhorn
  iThemba LABS, Somerset West
• l. Boscagli, A. Dainese, M. Poggi, R. Ponchia
  INFN/LNL, Legnaro, Padova

Equipment for non-destructive, two-dimensional beam profile measurement has been developed for the 15 MV tandem accelerator at INFN, Legnaro and the K200 variable-energy, separated-sector cyclotron at iThemba Labs. Ions, produced by the interaction of the beam with residual gas, are accelerated in an electrostatic field towards microchannel plates (MCP) for signal amplification. With the first of the two prototypes that were built, ions are collected in an electric field between two parallel plates and after passing through an aperture in one of the plates, move through the electric field between two curved plates and bend through an angle of ninety degrees before reaching the MCP. The spread in ion energies provides the second position. In the second prototype two one-dimensional systems, rotated through ninety degrees with respect to each other, were installed close together. The measured beam profiles for both systems were compared with those of measurements with a nearby profile grid. Measurements were made on various beams and intensities between 10 and 10{00} nA. The beam position display with the MCP was calibrated to within 0.75 mm with the profile grid.