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On the description of ground motion (LHC tunnel)

ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009). On the description of ground motion (LHC tunnel). C. Collette, F. Lackner, K. Artoos, M. Guinchard, C. Hauviller CERN/EN. Overview. Measurements description Ground motion modeling Lattice excitation

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On the description of ground motion (LHC tunnel)

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  1. ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009) On the description of ground motion (LHC tunnel) C. Collette, F. Lackner, K. Artoos, M. Guinchard, C. Hauviller CERN/EN

  2. Overview • Measurements description • Ground motion modeling • Lattice excitation • Example for a single quadrupole C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  3. K. Artoos and M. Guinchard, CLIC Workshop (16 October 2008) Measurements 1 km of optical fibre for synchronisation + timing and Data Transfer Parameters Sampling rate 256 Hz Block duration 64 s Average Lin – 50 Overlap 66.7 % 2 Muller-BBM MKII Analyzers 24 bit on 100 mV Low ADC noise Guralp CMG 40T x,y,z 2*800Vs/m 30 s -50 Hz ENDEVCO 86 C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009) PCB 393B31

  4. K. Artoos and M. Guinchard, CLIC Workshop (16 October 2008) LHC Measurements LHCDCUM 1000 ~ 80 m under ground Measurements: 0 1 2 3 4 5 6 7 8 9 10 12 20 30 38 54 108 198 306 412 509 604 706 960 (m) • Specificfeatures : • - Synchronousmeasurements • LHC systems in operation, night time • Multi-directional C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  5. Characteristics - Correlationfunction: - Cross spectral density: - Normalized spectral density between two measurements x(t) and y(t): • Power spectral density of the • relative motion d(t)=x1(t)-x2(t): C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  6. 3D coherences d=960 m; filteredbetween 0.08 Hz and 0.5 Hz • Correlation in the lowfrequency range • Similar amplitudes in all directions C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009) or ?

  7. 2D power spectral density (P2D) Seryi and Napoly, Phys. Rev. E 53 P2D contains all the information BUT does not depend on the position C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  8. Calculation of the P2D 1. From spectral densities of the relative measurements Continuous: Discrete: 2. Fromasymptoticbehaviour Zerothorder design report for the nextlinearcollider, pp 1011. C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  9. How to use the P2D Direct evaluation of the performances (Seryi and Napoly, Phys. Rev. E 53 ) 2. Transformitinto the time domain (Seryi et al): Random phases From 2D spectral density C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  10. Comparisonwithmeasurements Coherence using a theoretical model Calculatedfrommeasurement (Seryi and Napoly, Phys. Rev. E 53 ) How to account for local dynamics and local technical noise sources ? C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  11. Local dynamics Replaced by If girdersamplify by (Seryi, 2001) then 4 types of quadrupoles and modules C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  12. Local excitations Verticalground motion Additional technical noise: Reference Reference Ref. : C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  13. Local excitations Lateralground motion Additional technical noise: Reference Ref. : Reference C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  14. Explicit formulation Excitation matrix: C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  15. Lattice excitation matrix Motivation: Support location Measurements(available) Excitation matrix (objective) Procedure: for a few Li for any x1and x2 C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  16. Quadrupolestabilization a) 1 d.o.fquadrupole Objective: Beam size above 1 Hz: Control strategy: Feedback + Feedforward RMS integrated Objective (PAC 2009, Artoos et al) C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  17. b) 6 d.o.fquadrupole Excitation matrixwithout x-y coupling C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  18. Modal analysis of the 2m long quad. with 6 mounts Quadrupole resonances Quad. is a rigid body Model the quad. flexibility Mountsresonances C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  19. Modal coordinates where Seryi et al Standard calculations in finiteelement softwares (ANSYS, SAMCEF) C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  20. Comparison C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

  21. Conclusions • Update of 2D power spectral density for LHC tunnel in the vertical direction • 2D power spectral density for LHC tunnel in the lateral direction • Vertical and lateralmodels of the technical noise • Explicit formulation of the latticedynamics in the frequencydomain • Application to a single quadrupole C. Collette, ILC-CLIC LET Beam Dynamics Workshop (23-25 June 2009)

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