• H. Schmickler, M. Gasior, M. Guinchard, A.M. Kuzmin, J. Pfingstner, M.V. Sylte
  CERN, Geneva
• M.G. Billing
  CLASSE, Ithaca, New York
• M. Böge, M.M. Dehler
  PSI, Villigen

In the CLIC project, highest luminosity will be achieved by generation and preservation of ultra low beam emittances. It will require a mechanical stability of the quadrupoles down to 1 nm rms above 1 Hz through up to 24 km of linac structures. Studies are being undertaken to stabilize each quadrupole by an active feedback system based on motion sensors and piezoelectrical actuators. Since it will be very difficult to prove the stability of the magnetic field down to that level of precision, an attempt was made to use a synchrotron electron beam as a sensor and the beam motion was observed with a standard button BPM equipped with high resolution electronics. Hence in two consecutive experiments at CESR-TA (Cornell University, Wilson Lab) and at SLS (PSI-Villingen) the residual eigenmotion of the electron beam circulating in these two machines was measured in the frequency range 5–700 Hz. This paper describes in detail the achieved results alongside with purpose of the measurement, the equipment used for observation of the beam rest-motion, and the vibration measurements of mechanical machine elements.

Slides

• M. Wendt, A. Lunin, N. Solyak, V.P. Yakovlev
  Fermilab, Batavia
• N.C. Chritin, H. Schmickler, L. Søby
  CERN, Geneva

In the context of the development of a high resolution BPM system for the CLIC Main Linac we present the design of a cavity BPM prototype. It consists of a waveguide loaded dipole mode resonator and a monopole mode reference cavity, both operating at 15 GHz, to be compatible with the bunch frequencies at the CLIC Test Facility. Requirements, design concept, numerical analysis, and practical considerations are discussed.