• E. Todesco, N. Aquilina, B. Auchmann, L. Bottura, M.C.L. Buzio, R. Chritin, G. Deferne, L. Deniau, L. Fiscarelli, J. Garcia Perez, M. Giovannozzi, P. Hagen, M. Lamont, G. Montenero, G.J. Müller, S. Redaelli, RV. Remondino, F. Schmidt, R.J. Steinhagen, M. Strzelczyk, M. Terra Pinheiro Fernandes Pereira, R. Tomás, W. Venturini Delsolaro, J. Wenninger, R. Wolf
  CERN, Geneva
• N.J. Sammut
  University of Malta, Faculty of Engineering, Msida

The relation between field and current in each family of the Large Hadron Collider magnets is modeled with a set of empirical equations (FiDeL) whose free parameters are fitted on magnetic measurements. They take into account of residual magnetization, persistent currents, hysteresis, saturation, decay and snapback during initial part of the ramp. Here we give a first summary of the reconstruction of the magnetic field properties based on the beam observables (orbit, tune, coupling, chromaticity) and a comparison with the expectations based on the large set of magnetic measurements carried out during the 5-years-long production. The most critical issues for the machine performance in terms of knowledge of the relation magnetic field vs current are pinned out.

Slides

• G. Ambrosio, G. Chlachidze, M.J. Lamm, A. Nobrega, E. Prebys
  Fermilab, Batavia
• S. Caspi, H. Felice, P. Ferracin, G.L. Sabbi
  LBNL, Berkeley, California
• T.W. Markiewicz
  SLAC, Menlo Park, California
• J. Schmalzle, P. Wanderer
  BNL, Upton, Long Island, New York

The first Nb₃Sn Long Quadrupole (LQS01) designed and fabricated by the US LHC Accelerator Research Program (LARP) reached its target gradient of 200 T/m during the first test. LQS01 is a 90 mm aperture, 4 meter long quadrupole with Nb₃Sn coils made of RRP 54/61 strand (by Oxford Superconducting Technology). The two-layer coil design is based on the LARP 1m Technological Quadrupoles (TQC and TQS). The mechanical structure is based on the TQS structure implementing an aluminum shell preloaded by using bladders and keys. In 2005 LARP, in agreement with DOE and CERN, set the goal of reaching 200 T/m in a long Nb₃Sn quadrupole by the end of 2009. Achieving this goal in the first test shows the maturity reached by the Nb₃Sn technology for possible application to particle accelerators. Additional tests have been performed aiming at reproducing the performance of the most recent TQ models in order to demonstrate that there are no significant scale-up issues with this technology.

Slides

• J.M. Byrd, L.R. Doolittle, G. Huang, J.W. Staples, R.B. Wilcox
  LBNL, Berkeley, California
• J. Arthur, J.C. Frisch, W.E. White
  SLAC, Menlo Park, California

The scientific potential of femtosecond x-ray pulses at linac-driven FELs such as the LCLS is tremendous. Time-resolved pump-probe experiments require a measure of the relative arrival time of each x-ray pulse with respect to the experimental pump laser. In order to achieve this, precise synchronization is required between the arrival time diagnostic and the laser which are often separated by hundreds of meters. We describe an optical timing system based on stabilized fiber links which has been developed for the LCLS to provide this synchronization. Preliminary results show stability of the timing distribution at the sub-10 fsec level and overall synchronization of the x-rays and pump laser of less than 40 fsec. We present details of the implementation and LCLS and potential for future development.

Slides