Author: Cherif, A.
Paper Title Page
WEPPD029 The Mechanical Design of a Collimator and Cryogenic Bypass for Installation in the Dispersion Suppressors of the LHC 2567
  • D. Ramos, L. Alberty Vieira, A. Bertarelli, A. Cherif, N. Chritin, R. Claret, L. Gentini, D. Lombard, P. Minginette, P. Moyret, M. Redondas Monteserin, T. Renaglia, M.A. Timmins
    CERN, Geneva, Switzerland
  A project to install collimators in the dispersion suppressor regions of the LHC was launched early 2010, aiming to reduce the power deposition in superconducting magnets by a factor of 10. To be placed in the continuous arc cryostat, the design of such collimators had to comply with challenging integration, functional and time constraints. A pre-study for a cold collimator solution was launched in parallel with an alternative design consisting of a room temperature collimator and a cryogenic bypass. The second was eventually preferred, as it was based on proven LHC technologies for cryogenic, vacuum, electrical and collimator material solutions, despite the increased difficulty on the mechanical integration and assembly. This paper presents the mechanical design of a cryogenic bypass for the LHC continuous cryostat and respective collimator unit, both made to comply with the functionality of existing LHC systems. The approach taken to achieve a reliable design within schedule will be explained alongside the measures adopted to validate new solutions, in particular, when dealing with welding distortions, systems routing, thermal loads and precision mechanics.  
WEPPD073 Strategy and Validation of Fiducialization for the Pre-alignment of CLIC Components 2693
  • S. griffet, A. Cherif, J. Kemppinen, H. Mainaud Durand, V. Rude, G. Sterbini
    CERN, Geneva, Switzerland
  The feasibility of the high energy e+ e linear collider CLIC (Compact Linear Collider) is very dependent on the ability to accurately pre-align its components. There are two 20-km-long Main Linacs which meet in an interaction point (IP). The Main Linacs are composed of thousands of 2 m long modules. One of the challenges is to meet very tight alignment tolerances at the level of CLIC module: for example, the center of a Drive Beam Quad needs to be aligned within 20 μm rms with respect to a straight line. Such accuracies cannot be achieved using usual measurement devices. Thus it is necessary to work in close collaboration with the metrology lab. To test and improve many critical points, including alignment, a CLIC mock-up is being assembled at CERN. This paper describes the application of the strategy of fiducialization for the pre-alignment of CLIC mock-up components. It also deals with the first results obtained by performing measurements using a CMM (Coordinate Measuring Machine) to ensure the fiducialization, using a Laser Tracker to adjust or check components’ positions on a girder and finally using a Measuring Arm to perform dimensional control after assembling steps.