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Scarfe, A.

Paper Title Page
MOPP030 ATF2 Final Focus Orbit Correction and Tuning Optimisation 613
 
  • A. Scarfe, R. Appleby
    UMAN, Manchester
  • D. Angal-Kalinin, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  ATF2 is an upgrade to the ATF facility at KEK, Japan consisting of a replacement to the current ATF extraction line and the addition of a final focus section. The final focus system has been designed, and is aiming to test, the local chromaticity correction scheme as proposed for future linear colliders. The final focus system focuses the ultra-low emittance beams at the collision point in the linear collider. To provide the required small beam sizes and to maintain the beam sizes to nanometer level requires optimised orbit correction and tuning procedures. In this paper, the optimisation of the orbit correction using a global SVD method is discussed, along with the progress on final focus tuning knob analysis. The tuning algorithms used at ATF2 will provide an important feedback for future linear colliders (including the ILC and CLIC).  
TUPC087 4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line 1257
 
  • C. Rimbault, P. Bambade, J. Brossard
    LAL, Orsay
  • M. Alabau
    IFIC, Valencia
  • S. Kuroda
    KEK, Ibaraki
  • A. Scarfe
    UMAN, Manchester
  • M. Woodley
    SLAC, Menlo Park, California
 
  Emittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to vertical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emittance growth and find possible remedies. This requires efficient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods developed at SLAC and KEK have been used to estimate the vertical emittance, based on multiple location beam-size measurements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement errors and other fluctuations in beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their performance in the ATF EXT line.  
MOPP003 Study of Abnormal Vertical Emittance Growth in ATF Extraction Line 553
 
  • M. Alabau, A. Faus-Golfe
    IFIC (CSIC-UV), Valencia
  • M. Alabau, P. Bambade, J. Brossard, G. Le Meur, C. Rimbault, F. Touze
    LAL, Orsay
  • D. Angal-Kalinin, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Appleby, A. Scarfe
    UMAN, Manchester
  • S. Kuroda
    KEK, Ibaraki
  • G. R. White, M. Woodley
    SLAC, Menlo Park, California
  • F. Zimmermann
    CERN, Geneva
 
  Since several years, the vertical emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This long-standing problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experienced by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.