• K. Artoos, C.G.R.L. Collette, P. Fernandez Carmona, M. Guinchard, C. Hauviller, S.M. Janssens, A.M. Kuzmin, F. Lackner, R. Leuxe, A. Slaathaug
  CERN, Geneva

The CLIC main beam quadrupoles need to be stabilized to 1.5 nm integrated R.M.S. displacement at 1 Hz. The choice was made to apply active stabilization with piezoelectric actuators in a rigid support with flexural guides. The advantages of this choice are the robustness against external forces and the possibility to make fast incremental nanometre positioning of the magnet with the same actuators. The study and feasibility demonstration is made in several steps from a single degree of freedom system (s.d.o.f.) with a small mass, a s.d.o.f. with a large mass, leading to the demonstration including the smallest (type 1) and largest (type 4) CLIC main beam quadrupoles. The paper discusses the choices of the position and orientation of the actuators and the tailored rigidities of the flexural hinges in the multi degree of freedom system, and the corresponding MIMO control system. The compatibility with the magnet support and micrometer alignment system is essential. The status of the study and performed tests will be given.

• K. Artoos, C.G.R.L. Collette, P. Fernandez Carmona, M. Guinchard, C. Hauviller, S.M. Janssens, A.M. Kuzmin, A. Slaathaug, M.V. Sylte
  CERN, Geneva

A prerequisite for a successful nanometre level magnet stabilization and pointing system is a low background vibration level. This paper will summarize and compare the ground motion measurements made recently in different accelerator environments at e.g. CERN, CESRTA and PSI. Furthermore the paper will give the beginning of an inventory and characterization of some technical noise sources, and their propagation and influence in an accelerator environment. The importance of the magnet support is also mentioned. Finally, some advances in the characterization of the nanometre vibration measurement techniques will be given.