Simon, C.

Paper	Title	Page
TUPCH007	High Resolution BPM for the Linear Colliders	1004
	C. Simon, S. Chel, M. Luong, O. Napoly, J. Novo, D. Roudier CEA, Gif-sur-Yvette N. Rouvière IPN, Orsay
	The beam-based alignment and feedback systems which are essential for the operation of the future colliders use some high resolution Beam Position Monitors (BPM). In the framework of CARE/SRF, the task of CEA/DSM/DAPNIA (Saclay) is the design, the fabrication and the beam test of a BPM in collaboration with DESY. This system is composed of a RF re-entrant cavity with a beam pipe radius of 78mm and an analog electronics having several signal processing steps to reject the monopole mode. Thanks to its high position resolution (better than 1μm) and its high time-resolution (around 10ns), it is a candidate for the X-FEL at DESY and the ILC. Indeed the chosen coupling allows the bunch to bunch measurement and the separation between the monopole and dipole modes. Moreover, this BPM is designed to be used in a clean environment, at the cryogenic and room temperatures.
TUYPA02	High Precision SC Cavity Alignment Diagnostics with HOM Measurements	920
	J.C. Frisch, L. Hendrickson, J. May, D.J. McCormick, S. Molloy, M.C. Ross, T.J. Smith SLAC, Menlo Park, California N. Baboi, O. Hensler, L.M. Petrosyan DESY, Hamburg N.E. Eddy, S. Nagaitsev Fermilab, Batavia, Illinois O. Napoly, R. Paparella, C. Simon CEA, Gif-sur-Yvette
	Experiments at the TTF at DESY have demonstrated that the Higher Order Modes induced in Superconducting Cavities can be used to provide a variety of beam and cavity diagnostics. The centers of the cavities can be determined from the beam orbit which produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used as a high resolution beam position monitor, and the phase of the monopole modes to measure the beam phase relative to the accelerator RF. Beam orbit feedback which minimizes the dipole HOM power in a set of structures has been demonstrated. For most SC accelerators, the existing HOM couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional BPM.
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