1. Pre-isolator & QD0 support modeling 5th WG5 Meeting F. Ramos, A. Gaddi, H. Gerwig, N. Siegrist September 7, 2010

2. Layout 1Presented by H. Gerwig at the 15th MDI Meeting – 16/07/10 | Drawings by N. Siegrist

3. FE Model Layout 2 Things missing in the model: Pre-alignment mechanics Final doublet’s geometries (using, for now, 3-D point masses with estimated inertias) Final doublet’s supporting structures (girders, etc.) Pre-isolator’s supports (using, for now, 1-D springs with appropriate stiffnesses) LumicalBeamcalQD0SD0MULTQF1SF1

4. QD0 Support tube 3 The tuning of the tube´s eigenfrequencies led to the reinforced polygonal cross-section shown 630 493

5. Assumptions of the FE model 4 The pre-isolator mass is assumed to be made out of concrete and the remaining parts of stainless steel; The QD0’s yoke mass is supported by the inner tube while the coils’ mass is supported by the outer tube; Mass of the remaining elements extrapolated from QD0’s mass; Spring stiffness's tuned to yield fundamental eigenfrequencies of 0.7Hz and 1Hz in the horizontal and vertical directions respectively;

6. Main vibration modes 5 Mode # Frequency [Hz] 10.42 20.49 30.70 4 50.79 61.00 714.29 821.69 922.08 1033.53 1145.03 1251.19 1361.67 1463.61 1569.74 1670.68 1770.78 1877.13 1989.56 20105.57

7. Harmonic excitation in the vertical direction 6 Vertical steady-state response at QD0 1 Hz 51.2 Hz Good performance above the first resonance peak

8. Harmonic excitation in the horizontal directions 7 Vertical steady-state response at QD0 0.05 0.32 There is a good decoupling between the different directions

9. Out-of-phase vertical excitation 8 GOAL: Assess the impact of non-coherent ground motion UY=sin(ωt-90) UY=sin(ωt) UY=sin(ωt+90)

10. 9 Out-of-phase vertical excitation Vertical steady-state response at QD0 0.49 Hz Good performance despite the “lever arm” effect

11. 10 Random vibration response Ground motion measurements at CMS (A. Kuzmin – EDMS 1027459) Vertical ground motion @ YB0

12. Random vibration response 11 Vertical ground motion @ CMS-YB0 Vertical motion @ QD0

13. Random vibration response 12 Vertical ground motion @ CMS-YB0 Vertical motion @ QD0 4 Hz 2.9 nm 0.1 nm Reduction in r.m.s. displacements by a factor 30 above 4 Hz

14. Summary A detailed FE model of the pre-isolator and support tube was created; The main eigenfrequencies where chosen to be 0.7Hz and 1Hz in the horizontal and vertical directions respectively, to match the specifications of commercially available mounts; QD0’s support tube was tuned to have an eigenfrequency around 50Hz (51.2Hz); The harmonic analysis shows the system’s good vertical isolation performance above the first resonance peak while assuring a good decoupling between the different directions; The random vibration analysis confirms the good performance of the system, yielding a reduction by a factor 30 in r.m.s. displacements above 4Hz; The model will need to be improved with the addition of detailed geometry for the magnets, forward calorimeters, supporting girders, pre-alignment mechanics, etc.. 13

15. Spare Slides

16. Mode #1Mode #2 Mode #3Mode #4

17. Mode #5Mode #6 Mode #7Mode #8

18. Mode #9Mode #10 Mode #11Mode #12

19. Mode #13Mode #14 Mode #15Mode #16

20. Mode #17Mode #18 Mode #19Mode #20

21. Harmonic excitation in the vertical direction Steady-state response at QD0 in the transversal direction Steady-state response at QD0 in the beam direction

22. Harmonic excitation in the horizontal (transversal) direction Steady-state response at QD0 in the transversal direction Steady-state response at QD0 in the beam direction

23. Harmonic excitation in the horizontal (beam) direction Steady-state response at QD0 in the transversal direction Steady-state response at QD0 in the beam direction

24. Random vibration response at QD0 Excitation in the transversal direction Excitation in the beam direction Ground motion @ CMS-YB0 Vertical direction Beam direction Transversal direction Ground motion @ CMS-YB0 Vertical direction Beam direction Transversal direction