• R. Tomás, H.-H. Braun, J.-P. Delahaye, A. Marin, D. Schulte, F. Zimmermann
  CERN, Geneva
• D. Angal-Kalinin, J.K. Jones
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S. Bai, J. Gao, X.W. Zhu
  IHEP Beijing, Beijing
• P. Bambade, M. Renier
  LAL, Orsay
• Y. Honda, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• A. Scarfe
  UMAN, Manchester
• A. Seryi, G.R. White, M. Woodley
  SLAC, Menlo Park, California

The CLIC Final Focus System has considerably larger chromaticity than those of ILC and its scaled test machine ATF2. We propose to reduce the IP betas of ATF2 to reach a CLIC-like chromaticity. This would also allow to study the FFS tuning difficulty as function of the IP beam spot size. Both the ILC and CLIC projects will largely benefit from the ATF2 experience at these ultra-low IP betas.

• S. Bai, J. Gao, X.W. Zhu
  IHEP Beijing, Beijing
• A.S. Aryshev
  JAI, Egham, Surrey
• P. Bambade, T. Okugi
  KEK, Ibaraki
• Y. Kamiya
  ICEPP, Tokyo
• D.J. McCormick, M. Woodley
  SLAC, Menlo Park, California
• M. Oroku, T. Yamanaka
  University of Tokyo, Tokyo

Funding: NSFC 10525525 and 10775154. CNRS-IN2P3 and ANR.

The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. We report on techniques developed based on simulation studies to adjust the horizontal and vertical beam waists independently in the presence of errors, at two different IP locations where the beam size can be measured with different accuracies. During initial commissioning, we will start with larger than nominal β-functions at the IP, to reduce the effects from higher-order optical aberrations and thereby simplify the optical corrections needed. The first measurements in such intermediate β-configurations are reported.