Author: Charles, T.K.
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MOPRB001 Low Emittance Tuning of FCC-ee 574
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • S. Aumon, B.J. Holzer, F. Zimmermann
    CERN, Meyrin, Switzerland
  • K. Oide
    KEK, Ibaraki, Japan
  
  The FCC-ee project studies the design of a future 100 km e+/e− circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1036 cm-2s-1. In order to reach these luminosity requirements, extreme focusing is needed in the interaction regions. For the Z energy (45.6 GeV) lattice, the maximum beta value is 8322 m, and the vertical beta function is 0.8 mm at the IP. These aspects of the FCC-ee lattice make it particularly susceptible to misalignments and field errors, and therefore present an appreciable challenge for emittance tuning. A challenging correction scheme is proposed to reduce the coupling and the vertical emittance. We describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes special programs, that had been developed to optimise the lattice based on Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices. Thousands of misalignment and field error random seeds were introduced in MADX simulations and the final corrected lattices are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB001  
About • paper received ※ 09 April 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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WEYYPLS2 First Experimental Measurements of the Caustic Nature of Trajectories in Bunch Compressors 2270
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • J. Björklund Svensson
    Lund University, Lund, Sweden
  • A. Latina
    CERN, Geneva, Switzerland
  • S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  Theoretical advancements describing density perturbations in accelerated charge particle beams, known as caustics, has been recently developed * This proceeding describes the first experimental measurements of the caustic nature of charged particle trajectories in a particle accelerator. Caustics by their nature are discontinuities that result from small continuous perturbations of an input. Under certain conditions, small density modulations will reliably produce striking changes in the corresponding output current profile. These current modulations can shift alone the bunch with varying higher-order longitudinal dispersion. The MAX IV linac double-bend achromats provide the perfect test bed for experimentally verifying how the caustic lines evolve. The natural amplification of small perturbations makes caustics an attractive diagnostic tool, and effective tool for characterise the bunch compressors. This approach also allows us to modify and improve the longitudinal charge profile, removing current spikes or creating tailor shaped current profiles.
* T.K.Charles et. al. Phys. Rev. Accel. Beams 19, 104402 		 
slides icon Slides WEYYPLS2 [5.402 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS2  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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