• A. Samoshkin, D. Gudkov, G. Riddone
  CERN, Geneva

The CLIC (Compact LInear Collider) design is based on two-beam acceleration concept developed at CERN, where the RF power is generated by a high current electron-beam (Drive Beam) running parallel to the Main Beam. The Drive Beam is decelerated in special power extraction structures (PETS) and the generated RF power is transferred via waveguides to the accelerating structures (AS). The accelerating gradient must be very high (100 MV/m) to reach the high energy for the electron-positron collisions. To facilitate the matching of the beams, components are assembled in 2-m long modules, of few different types. In some of them the AS are replaced by quadrupoles used for the beam focusing. Their alignment and positioning is made by using the signals from the beam-position monitors (BPM). Special modules are needed in damping region or to carry out dedicated instrumentation and vacuum equipment. The module design and integration has to cope with challenging requirements from the different technical systems. This paper reports the status of the engineering design and reports on the main technical issues.

• F. Peauger, W. Farabolini, P. Girardot
  CEA, Gif-sur-Yvette
• A. Andersson, G. Riddone, A. Samoshkin, A. Solodko
  CERN, Geneva
• R.J.M.Y. Ruber
  Uppsala University, Uppsala
• R. Zennaro
  PSI, Villigen

To achieve high luminosity in CLIC, the accelerating structures must be aligned to an RMS accuracy of 5 μm with respect to the beam trajectory. Position detectors called Wakefield Monitors (WFM) are integrated to the structure for a beam based alignment. This paper describes the requirements of such monitors. The development plan and basic feature of the WFM as well as the accelerating structure working at 12 GHz and 100 MV/m are shortly described. Then we focus on detailed electromagnetic simulations and design of the WFM itself. In particular, time domain computations are performed and an evaluation of the intrinsic resolution is done for two higher order modes at 17 and 24 GHz. The mechanical design of the accelerating structure with WFM is also presented. Precise machining with a tolerance of 2.5 μm and a surface roughness of 0.025 μm is demonstrated. The fabrication status of three complete accelerating structures with WFM is finally presented for a feasibility demonstration with beam in CTF3 at CERN.