Author: Missiaen, D.P.
Paper Title Page
WEPME041 The Distance from CERN to LNGS 3016
  • M.A. Jones, I. Efthymiopoulos, D.P. Missiaen
    CERN, Geneva, Switzerland
  Obviously the distance between the CNGS Target at CERN and the LNGS Opera experiment cannot be measured directly and in fact requires the combination of three independent sets of measurements: two to link underground reference points at each site to corresponding points on the surface; and a third to link the surface points at both sites. Until the Opera results raised questions about the speed at which neutrinos travelled, the main alignment concern for the CNGS beamline had been an orientation problem -to ensure that the beamline arrived to within ~100 m of its target at LNGS. GPS measurements at the two sites, and the use of gyro-theodolite measurements in the tunnel at CERN, ensured that the absolute alignment of the beamline was established to the required accuracy. New determinations of the links between the surface and the tunnel were not considered necessary until interest grew in the distance between the sites, at which point additional measurement campaigns were organised in order to further reduce the uncertainty in the distance. Details of all these campaigns and the distance estimates will be given.  
WEPME046 Alignment Challenges for a Future Linear Collider 3031
  • H. Mainaud Durand, D.P. Missiaen, G. Stern
    CERN, Geneva, Switzerland
  The preservation of ultra-low emittances in the main linac and Beam Delivery System area is one of the main challenges for linear colliders. This requires alignment tolerances never achieved before at that scale, down to the micrometre level. As a matter of fact, in the LHC, the goal for the smoothing of the components was to obtain a 1σ deviation with respect to a smooth curve of 0.15 mm in a 150 m long sliding window, while for the CLIC project for example, it corresponds to 10 micrometres over a sliding window of 200m in the Beam Delivery System area. Two complementary strategies are being studied to fulfill these requirements: the development and validation of long range alignment systems to propagate precision and accuracy over a few hundreds of metres and short range alignment systems over a few metres. The studies undertaken, with associated test setups and the latest results will be detailed, as well as their application for the alignment of both CLIC and ILC colliders.