Author: Gibson, S.M.
Paper Title Page
WEAO04 Beam Measurements at the CERN SPS Using Interferometric Electro-Optic Pickups 454
 
  • A. Arteche, A. Bosco, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • S.E. Bashforth, A. Bosco, S.M. Gibson
    JAI, Egham, Surrey, United Kingdom
  • M. Krupa, T. Lefèvre
    CERN, Geneva, Switzerland
 
  Funding: Work supported by UK STFC grants ST/N001583/1, JAI at Royal Holloway University of London and CERN.
Since 2016 a prototype electro-optic pickup has been installed on the SPS as part of the ongoing development of a high bandwidth electro-optic beam position monitor for the High Luminosity LHC. Following the success of initial beam signal observations with the prototype, improvements of the sensitivity and stability of the pickup have become the main focus of the project. A new concept has been developed which uses an interferometric technique to measure the image field of a passing bunch. One arm of an interferometer passes through an electro-optic lithium niobate crystal, embedded in a pickup, whereas the other arm bypasses. The recombination after the pickup results in an interference pattern that changes as a bunch passes by, due to the electro-optic response of the crystal to the image field. This technique enhances the sensitivity to the field and improves control of the working point. Results from high intensity beams at the SPS are presented. These include a comparison between two different interferometric configurations that were tested on different pickups with similar beam conditions. The stability is assessed by frequency scanning interferometry during beam operation.
 
slides icon Slides WEAO04 [52.252 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO04  
About • paper received ※ 10 September 2019       paper accepted ※ 12 September 2019       issue date ※ 10 November 2019  
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TUBO04 Measuring the Beam Profile by Counting Ionization Electrons 252
 
  • H.S. Sandberg, W. Bertsche
    UMAN, Manchester, United Kingdom
  • D. Bodart, B. Dehning, S. Levasseur, H.S. Sandberg, G. Schneider, J.W. Storey, R. Veness
    CERN, Geneva, Switzerland
  • S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  The principle of non-destructive beam profile measurement with rest gas ionization electrons has remained largely unchanged since the technique was first proposed in the late 1960’s. Ionization electrons (or ions) are transported by an electrostatic field onto an imaging detector, where the spatial distribution of detected electrons is a direct measure of the transverse beam profile. The detector typically consists of one or more Micro-Channel Plates (MCP’s) to amplify the signal, followed by either a phosphor screen and camera, or pickup electrodes. A long-standing problem is the ageing of the MCP’s, which limits the accuracy of the beam profile measurement. A new technique to detect ionization electrons has been developed at CERN, which uses a hybrid pixel detector to detect single ionisation electrons. This allows the application of counting statistics to the beam profile measurement. It will be shown that a meaningful beam profile can be extracted from only 100 electrons. Results from the new instrument will be presented, which demonstrate the ability to measure the beam profile of single bunches turn-by-turn, which offers new opportunities for beam diagnostic insights.  
slides icon Slides TUBO04 [2.199 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUBO04  
About • paper received ※ 03 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)