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Published byPatrick Bruce Modified over 9 years ago
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1 KEK Cavity BPM Hitoshi Hayano Development of Cavity BPM for Q-magnet attachment, Aiming; compact design, 0.2µm resolution, BPM center error (between electrical and mechanical) <10µm, Simple & cheap electronics design Vide-meeting 3/24/2005 ILC-Asia
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2 Design concept Use dipole mode excitation in a pill-box cavity principle Concept of Q-mag attachment
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3 Measurement of center difference between electrical and mechanical Alignment and scanning device Cavity cold Model Excitation antenna Cold model cavity on the measuring device アンテナ スキャン結果
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4 Proto-type of Cavity BPM pickup Feature : frequency : 6.55GHz(TM110) magnetic coupling by 4 slots into resonant wave-guide 4-port pickup by antenna(electrical field) (additional common-mode rejection by external combiner ) reference cavity attached: 6.55GHz(TM010)
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5 Detail of inner structure (low-power model) same as hot-model
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6 Electronics for position detection (Analog signal process type) Frequency converter 6.5GHz -> 714MHz Phase detector 714MHz burst -> pulse signal Charge ADC
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7 3 BPM setup for resolution measurement in ATF L1L1 L2L2 x1x1 x2x2 x3x3 X 2 esti =(L 2 x 1 + L 1 x 3 )/(L 1 +L 2 ) X 2 esti x2x2 X’ Y’ Y’ =(x 2 - x 2 esti )/sqrt(2) 45deg axis rotation, and projection to Y’ Sigma; Y’ =sqrt( x2 2 + (L 2 /(L 1 +L 2 )) 2 x1 2 + (L 1 /(L 1 +L 2 )) 2 x3 2 )/sqrt(2) If L 1 =L 2, x1 = x2 = x3 = x ; Y’ = sqrt(3)/2 x beam resolution Measured spread (45deg projection) Achieved resolution : 0.07 μ m
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8 Development Status Developed Item ( 2002-2004 ): 1. Electrical center measurement device (2µm precision) 2. Cold model 1 set 3. Hot model 3 BPMs 4. Electronics 3 sets This year plan ( 2005 ): 1. Improvement of scanning antenna of center measurement device 2. Improvement of electronics; limiter amplifier before phase detection, more signal gain, reduce thermal noise, etc.
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9 For ATF2 Quad-BPM Q-BPM : 1. ready to install in Oct. 2006, ready to operate in Feb. 2007 2. BPM pickup : Total 21(?), (by PAL?) 3. Electronics : digital conversion(?), (by SLAC?) 4 . drawings : supply by KEK(?) 5 . feedthrough : supply by KEK Pickup design plan : 1. Use existing KEK-cavity BPM design? X-Y isolation only 20dB, signal tend to small, coupling slot too large?, resonant waveguide working or not?, … or 2. Develop new design? (modify KEK-cavity?) start HFSS calculation, make cold model, antenna scan measurement, then hot model….
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