Vibration Measurement on the Shintake Monitor and Final Doublet Takashi Yamanaka (Univ. of Tokyo) Benoît Bolzon (LAPP) ATF2 weekly meeting 26 November, 2008

Introduction measured the vibration on the Shintake monitor table and Final Doublet respectively also measured the correlation between Shintake monitor table and Final Doublet compared the measured vibration with the tolerance required from beam size measurement at the IP Shintake monitor table and QF1measurement between Shintake monitor table and QD0

Measured Position on the Shintake Monitor Table Electron Beam We measured vibration on the top the vertical table. The electron beam passes through the center of the table Since the laser interferometer optics is constructed on the whole area of the vertical table, it is not a overestimate. Shintake monitor vertical table

Vibration Sensors ModelCMG-40T86MG-102S ManufacturerGuralp SystemsEndevcoTOKKYO KIKI Sensor TypeVelocimeterAccelerometer Response Frequency0.03 ~ 50 Hz0.01 ~ 100 Hz0.1 ~ 400 Hz Direction3-directionvertical only1-drection each Sensors have wider response frequency but because of the electric noise, measureable frequency range is restricted to 0.2 ~ 100 Hz. We used velocimeters for 0.2 ~ 13 Hz and accelerometer for 13 ~ 100 Hz

Measurement Conditions Window: Hanning Averaging: Linear and 50 averages Overlap: % Frequency Resolution: Hz 1 measurement interval: 1 minute Maximum Frequency: 100 Hz

Measurement on Shintake Monitor Table Transfer function from floor to the Shintake monitor table flat below 10 Hz Peak appears around 50 Hz Coherence between floor and the Shintake monitor table equals to one below 10 Hz decreases above 10 Hz in horizontal directions In vertical, coherence is good up to 60 Hz

Integrated Vibration of the Shintake Monitor Table Integrated vibration of the Shintake monitor table relative to the floor large increase around 50 Hz almost flat below 10 Hz seems to increase below 0.5 Hz but it is due to the low S/N ratio and not the actual motion

Measurement on QD0 Transfer function from floor to QD0 S flat below 10 Hz Peak appears around 20 Hz in horizontal directions Peak appears around 60 Hz in vertical direction Coherence between floor and QD0 equals to one below 10 Hz decreases above 10 Hz in horizontal directions In vertical, coherence is good up to 80 Hz

Integrated Vibration of QD0 Integrated vibration of QD0 relative to the floor Increase around 50 Hz large increase around 20 Hz in horizontal directions almost flat below 10 Hz

Measurements between QD0 and QF1 Phase between QD0 and QF1 equals to zero below 10 Hz Being high above 10 Hz in direction parallel to beam Being high only above 50 Hz in direction perpendicular to beam In vertical, phase is good up to 60 Hz Transfer function from QF1 to QD0 flat below 10 Hz Each peak of QD0 and QF1 around 20 Hz appears in direction parallel to the beam No peaks appear in the vertical direction Peak disappears around 20Hz in direction perpendicular to the beam  QDO and QF1 moves in phase in vertical directions and in direction perpendicular to beam

Transfer Function from Final Doublet to Shintake Monitor Almost same result for QD0 and QF1 Magnitude of transfer function - is flat below 10 Hz in all directions because of good coherence - decreases around 20 Hz in horizontal directions because of the vibration of the Final Doublet - increases above 50 Hz in horizontal directions because of the vibration of the Shintake monitor table

Coherence Between Final Doublet and Shintake Monitor Coherence - equals to one below 10 Hz - decrease above 40 Hz for QD0 in vertical - decrease above 10 Hz for QF1 because of longer distance

Integrated Relative Motion between Final Doublet and Shintake Monitor Almost the same result for QD0 and QF1. Vibration in vertical direction is relatively small. In horizontal two directions, vibrations are the same level. Increase above 50 Hz mainly comes from Shintake monitor Increase around 20 Hz mainly comes from Final Doublet

Tolerance (1) Vertical 37 nm beam size measurement is aimed. Relative motion between Final Doublet and Shintake monitor becomes the measurement error at the beam size measurement. Less than 10 nm stability is needed for QD0. 2 % beam size error corresponds to 7 nm position jitter for QD0 and 20 nm for QF1 according to the ATF2 Proposal.

Tolerance (2) Perpendicular to beam (horizontal) 2.8 μm beam size measurement only sub-micron stability is required

Tolerance (3) Parallel to beam Vibration causes the fluctuation of beam waist position Beam size development along the beam axis can be written as follows, vertical beta function at the IP, is about 100 μm when 37 nm vertical beam size less than several tens of micron stability is needed

Measurement Results and Tolerances ToleranceMeasurement (between QD0) Measurement (between QF1) vertical7 nm (for QD0) 20 nm (for QF1) 4.8 nm6.3 nm perpendicular to beam ~ 500 nm30.7 nm30.6 nm parallel to beam ~ 10,000 nm36.5 nm27.1 nm Vibration condition sufficiently meets the requirement for the beam size measurement in horizontal direction. In vertical the tolerance is the most strict but the stability is proved to satisfy the requirement from the beam size measurement