Fiducialisation and initial alignment of CLIC component with micrometric accuracy

We propose a new solution to fiducialise the three major components of the CLIC collider: quadrupoles, beam-position monitors (BPM), and accelerating structures (AS). This solution is based on the use of a copper-beryllium (CuBe) wire to locate the reference position, i.e. the symmetry axes of the components (their magnetic, respectively electromagnetic centre axis), and to determine their position in the common support assembly defining a local coordinate system, with respect to the fiducials. These alignment targets will be used later to align the support assembly in the tunnel. With such a method, several accelerator components of different types, supported by a dedicated adjustment system, can be simultaneously fiducialised and pre-aligned using the same wire, enabling a micrometric accuracy with help of a 3D coordinate measurement machine (CMM). Alternative solutions based on frequency scanning interferometry (FSI) and micro-triangulation are also under development, to perform such fiducialisation and initial alignment directly in the tunnel after transport of the components on their common support. Complementary studies have also been undertaken on the development of a new seismic sensor, on a high-stiffness nano-positioning system with a millimetre stroke, on miniature rotating search coils, and on the extrapolation of the uncertainties of measurements considering variations of temperature. These developments are part of the PACMAN project (a study on Particle Accelerator Components’ Metrology and Alignment to the Nanometre scale), an innovative Doctoral Programme, where 10 PhD students hosted at CERN work towards their PhD thesis. The methods and tools being developed are presented in this paper, as well as the first results obtained.