Dirk Mergelkuhl
Engineer Experiment Metrology of Large Scale Metrology Section
CERN
Switzerland

Biography
After his Diploma as Surveying Engineer at the University of Applied Sciences in Oldenburg, Germany, Dirk Mergelkuhl *1974 in Borgholzhausen, Germany, worked in the ERSO research project as photogrammetrist and software engineer at the Technical University of Darmstadt. In 2000 he joined the Large Scale Metrology Section at European Organization for Nuclear Research (CERN), Geneva, Switzerland. He is responsible for the alignment work for several experiments linked to different particle accelerators. His main focus is actually on the alignment of the ATLAS Experiment of CERN’s Large Hadron Collider (LHC).

Abstract
Large Scale Metrology at CERN

The European Organization for Nuclear Research (CERN) is the world’s largest institute for particle accelerators and high energy physics. It hosts among others the Large Hadron Collider (LHC) that is with 27 km the largest particle accelerator in the world and the related physics detectors. A long shut down takes place 2013/14 in order to consolidate the LHC allowing in the future an energy of 7 TEV. For the exploitation of these most complex scientific instruments the alignment of components is crucial as it has a direct influence on the performance. The large scale metrology section is responsible for the metrology and alignment works of more than 60 km of beam lines and of the detectors at CERN. The shutdown is used by the survey team to re-measure all the components of the LHC and to do intensive maintenance for the detectors. Different measurement demands with the corresponding techniques such as laser tracking and close range photogrammetry for interventions in the accelerators and experiments are presented and illustrated by examples. An outlook is given on permanent alignment systems under study to cope with the constraints as high vacuum, temperature close to the absolute zero and extreme geometrical precision for the next accelerators.