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CLIC final doublets No active stabilization?

CLIC final doublets No active stabilization?. Benoît BOLZON. CLIC stabilization meeting 5, 31/03/09. Context. Shintake Monitor: Instrumentation of the beam. Final doublets. Final focus system. ATF2 specifications for final focus vibrations.

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CLIC final doublets No active stabilization?

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  1. CLIC final doublets No active stabilization? Benoît BOLZON CLIC stabilization meeting 5, 31/03/09

  2. Context Shintake Monitor: Instrumentation of the beam Final doublets Final focus system

  3. ATF2 specifications for final focus vibrations • First goal: obtain a vertical beam size of 37nm • Shintake monitor (SM): beam size measurement (interferometer) Vertical relative motion between SM and final doublets above 0.1Hz: QD0: 7nm and QF1: 20nm (2% error on beam size) • Distance between final doublets and the IP not to far SM  Good ground motion coherence measured on site QF1 QD0 Rigid fixation to the floor with independant stiff supports 3m 1m50

  4. Measurements between [QD0; QF1] and the floor Transfer function magnitude • Only one resonance at 66Hz due to supports between FD and table • Coherence good up to 80Hz • Totally flat and at 1 below 10 Hz (high ground motion) Magnets and supports very rigid Good fixation of supports to the floor

  5. Measurements between [QD0; QF1] and the floor Integrated RMS of relative motion If no resonance • Almost flat below 60Hz • 10nm of relative motion due to the resonance at 66Hz • Factor 14 of damping above 1Hz • If resonance above 100Hz, may have damping factor of 130 above 1Hz

  6. Relative motion between CLIC final doublets Relative motion calculationbetween ATF2 FF for different distances ? QF1 QD0 QD0 QF1 1) 3) 2) (different distances) 3 levels of PSD chosen 1) TF between ATF2 QF1FF and the floor (measured at ATF2) × 2) Floor TF between two ATF2 QF1FF for different distances (measured at ATF2) × 3) TF between ATF2 QF1FF and the floor (measured at ATF2) 3 levels of PSD chosen = Integrated RMS of relative motion between FD

  7. Relative motion between CLIC final doublets ATF2 ground motion coherence for different distances • Fall of coherence with the distance • Distance of 3m: slightly fall above 3Hz, big fall above 10Hz

  8. Relative motion between CLIC final doublets 3 levels of absolute PSD chosen

  9. Relative motion between CLIC final doublets For ATF2 ground motion (veryhigh) • Increase of relative motion with distance • Above 1Hz, absolute motion of 128.4nm •  d=3m, relative motion of 12.3nm (factor 10) •  d=4m, relative motion of 15.6nm (factor 8.2) •  d=5m, relative motion of 24.6nm (factor 5.2) •  d=10m, relative motion of 37.0nm (factor 3.7)

  10. Relative motion between CLIC final doublets For LHC ground motion (low) • Increase of relative motion with distance • Above 1Hz, absolute motion of 12.5nm •  d=3m, relative motion of 1.0nm (factor 12.5) •  d=4m, relative motion of 1.3nm (factor 9.6) •  d=5m, relative motion of 1.8nm (factor 6.9) •  d=10m, relative motion of 3.1nm (factor 4.0)

  11. Relative motion between CLIC final doublets For LAPP ground motion at night (verylow) • Increase of relative motion with distance • Above 1Hz, absolute motion of 3.0nm •  d=3m, relative motion of 0.4nm (factor 7.5) •  d=4m, relative motion of 1.1nm? (factor 2.7?) •  d=5m, relative motion of 0.7nm (factor 4.3) •  d=10m, relative motion of 0.9nm (factor 3.3) 50Hz noise

  12. Conclusion • Integrated RMS of relative and absolute motion between ATF2 QF1FF (rigid magnets!) above 1Hz with a rigid fixation: • Damping factor above 1Hz of ~10 if final doublets separated of 3m!! • For a ground motion of 3nm above 1Hz, relative motion of (/3.3)only 0.4nm if final doublets separated of 3m!! • If tolerances are released (1nm), distance of 10m OK (specification now) for LAPP ground motion (or LHC ground motion OK for dist of 4m)

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