Accelerator and Technical Sector Seminar: Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution

Thursday 24 November 2010
Accelerator and Technical Sector Seminar
at 14:15  -  BE Auditorium, bldg. 6 (Meyrin) – please note unusual place

Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution
Stef Janssens /EN-MME

Abstract: To reach the required luminosity at the CLIC interaction point, about 4000 quadrupoles are needed to obtain a vertical beam size of 1 nm at the interaction point. The mechanical jitter of the quadrupole magnets will result in an emittance growth. An active vibration isolation system is required to reduce vibrations from the ground and from external forces to about 1.5 nm integrated root mean square (r.m.s.) vertical displacement at 1 Hz. A short overview of vibration damping and isolation strategies will be presented as well as a comparison of existing systems. The unprecedented resolution requirements and the instruments enabling these measurements will be discussed. The vibration sources from which the magnets need to be isolated are characterised. The specificity of the requirements for isolation of particle accelerator components resulted in the development of a very stiff stabilization support at CERN. The active support can also reposition the quadrupole in between beam pulses with nanometre resolution. The conceptual design of the active stabilization and nano-positioning was validated in models and experimentally demonstrated on test benches. The design choices and improvements for the mechanics, the controller and electronics, leading to the results achieved, will be shown. The integration of the stabilisation system with other ground motion mitigation techniques has provided additional input for the stabilisation system. Finally, the status and directions of future development work will be presented.

Organisers: S. Sgobba (EN), W. Herr (BE), G. de Rijk (TE)