Author: Bravin, E.
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MOPF14 Vertical Beam Size Measurement at CesrTA Using Diffraction Radiation 77
 
  • L.M. Bobb, T. Aumeyr, P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • T. Aumeyr, P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  • M.G. Billing, J.V. Conway
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • L.M. Bobb
    DLS, Oxfordshire, United Kingdom
  • E. Bravin, T. Lefèvre, S. Mazzoni, H. Schmickler
    CERN, Geneva, Switzerland
 
  Over recent years the first Diffraction Radiation (DR) beam size monitor has been tested on a circular machine. At CesrTA, Cornell University, USA, the sensitivity and limitations of the DR monitor for vertical beam size measurement has been investigated. DR emitted from 1 and 0.5 mm target apertures was observed at 400 and 600 nm wavelengths. In addition, interference between the DR signals emitted by the target and mask has been observed. In this report, we present the recent observations and discuss areas for improvement.  
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MOPF15 Status of and Future Plans for the CERN LINAC4 Emittance Meter based on Laser Electron-Detachment and a Diamond Strip-Detector 83
 
  • T. Hofmann, E. Bravin, U. Raich, F. Roncarolo, F. Zocca
    CERN, Geneva, Switzerland
  • G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
    Royal Holloway, University of London, Surrey, United Kingdom
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
 
  Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191
LINAC4 has started its staged commissioning at CERN. After completion it will accelerate high brightness H beams to 160 MeV. To measure the transverse profile and emittance of the beam, a non-destructive method based on electron photo-detachment is proposed, using a pulsed, fibre-coupled laser to strip electrons from the H ions. The laser can be focused and scanned through the H beam, acting like a conventional slit. A downstream dipole separates the neutral H0 beamlet, created by the laser interaction, from the main H beam, so that it can be measured by a diamond strip-detector. Combining the H0 beamlet profiles with the laser position allows the transverse emittance to be reconstructed. A prototype of this instrument was tested while commissioning the LINAC4 at 3 and 12 MeV. In this paper we shall describe the experimental setup, challenges and results of the measurements, and also address the characteristics and performance of the diamond strip-detector subsystem. In addition, the proposal for a permanent system at 160 MeV, including an electron detector for a direct profile measurement, will be presented.
 
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MOPD11 Near-Saturation Single-Photon Avalanche Diode Afterpulse and Sensitivity Correction Scheme for the LHC Longitudinal Density Monitor 169
 
  • M. Palm, E. Bravin, S. Mazzoni
    CERN, Geneva, Switzerland
 
  Funding: CERN
Single-Photon Avalanche Diodes (SPADs) monitor the longitudinal density of the LHC beams by measuring the temporal distribution of synchrotron radiation. The relative population of nominally empty RF-buckets (satellites or ghosts) with respect to filled bunches is a key figure for the luminosity calibration of the LHC experiments. Since afterpulsing from a main bunch avalanche can be as high as, or higher than, the signal from satellites or ghosts, an accurate correction algorithm is needed. Furthermore, to reduce the integration time, the amount of light sent to the SPAD is enough so that pile-up effects and afterpulsing cannot be neglected. The SPAD sensitivity has also been found to vary at the end of the active quenching phase. We present a method to characterize and correct for SPAD deadtime, afterpulsing and sensitivity variation near saturation, together with laboratory benchmarking.
 
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WEPF07 Optimization of a Short Faraday Cup for Low-Energy Ions Using Numerical Simulations 544
 
  • A.G. Sosa, E. Bravin, E.D. Cantero
    CERN, Geneva, Switzerland
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330.
ISOLDE, the heavy-ion facility at CERN is undergoing a major upgrade with the installation of a superconducting LINAC that will allow post-acceleration of ion beams up to 10 MeV/u. In this framework, customized beam diagnostics are being developed in order to fulfill the design requirements as well as to fit in the compact diagnostic boxes foreseen. The main detector of this system is a compact Faraday cup that will measure beam intensities in the range of 1 pA to 1 nA. In this contribution, simulation results of electrostatic fields and particle tracking are detailed for different Faraday cup prototypes taking into account the energy spectrum and angle of emission of the ion-induced secondary electrons.
 
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WEPF13 The Status of Beam Diagnostics for the Hie-Isolde Linac at Cern 565
 
  • E.D. Cantero, W. Andreazza, E. Bravin, A.G. Sosa
    CERN, Geneva, Switzerland
  • A.G. Sosa
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.G. Sosa
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330.
The HIE-ISOLDE project aims at upgrading the CERN ISOLDE radioactive ion beam facility for higher beam intensities and higher beam energies. New beam diagnostic devices have to be developed as part of this upgrade, in particular for the measurement of intensity, energy, transverse and longitudinal profiles, and transverse emittance. The beam energy ranges from 300 keV/u to 10 MeV/u and beam intensities are between 1 pA and 1 nA. Faraday cups will be used for the measurement of the beam intensity while silicon detectors will be used for the energy and longitudinal profile measurements. The transverse profiles will be measured by moving a V-shaped slit in front of a Faraday cup and the beam position will be calculated from the profiles. The transverse emittance can be measured using the existing REX-ISOLDE slit and grid system, or by the combined use of two scanning slits and a Faraday cup. The final design of the mentioned devices will be presented in this contribution, including the results of the experimental validation tests performed on prototypes during the last two years.
 
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