Cavity BPM System Tests for the ILC Spectrometer

Authors :: Slater, M.
Adolphsen, C.
Arnold, R.
Boogert, S.
Boorman, G.
Gournaris, F.
Hildreth, M.
Hlaing, C.
Jackson, F.
Khainovski, O.
Kolomensky, Yu. G.
Lyapin, A.
Maiheu, B.
McCormick, D.
Miller, D. J.
Orimoto, T. J.
Szalata, Z.
Thomson, M.
Ward, D.
Wing, M.
Woods, M.
Publication Year :: 2007
Abstract: The main physics programme of the International Linear Collider (ILC) requires a measurement of the beam energy at the interaction point with an accuracy of $10^{-4}$ or better. To achieve this goal a magnetic spectrometer using high resolution beam position monitors (BPMs) has been proposed. This paper reports on the cavity BPM system that was deployed to test this proposal. We demonstrate sub-micron resolution and micron level stability over 20 hours for a $1\m$ long BPM triplet. We find micron-level stability over 1 hour for 3 BPM stations distributed over a $30\m$ long baseline. The understanding of the behaviour and response of the BPMs gained from this work has allowed full spectrometer tests to be carried out.<br />Comment: Paper submitted to Nuclear Instruments and Methods. 35 pages, 23 figures