QD0 stabilisation in CLIC CDR A.Jeremie with LAViSta team

What can be part of the CDR? Introduction with specs: 0.1nm at 4Hz but can be revised with beam- feedback performance: – Why: because detector moves much more than specs (CMS measurements?) – Isolation from GM – Compensation of resonance peaks Feasibility already demonstrated (the successive PhDs) : – Isolation on commercial TMC table (x10) – Compensation of resonances with LAPP feedback (X3) – Tests done in laboratory environment Feasibility to be demonstrated: – Isolation on compact device to fit in tight space – Has to work in magnetic field and radiation environment – How to integrate with the rest (cantilever or Gauss points) – Compatibility with beam feedback and pre-alignment – Modal analysis and vibration measurements on QD0 (here or in QDO part?) 2A.Jeremie MDI - CLIC CDR, May

CMS top of Yoke measurement PSD of the signals Vertical direction Geophones PSD of the signals Beam direction Cooling system OFF 100 nm Why: because detector moves much more than specs (CMS measurements?)

Andrea JEREMIE 4 Example of spectral analysis of different disturbance sources Acoustic disturbance : Amplified by the structure itself : the eigenfrequencies Ground motion : Seismic motion Cultural noise A pink noise on a large bandwidth =>need to isolate and compensate Introduction with specs: 0.1nm at 4Hz but can be revised with beam- feedback performance:

5 Some comments Several PhDs: –C.Montag (DESY) 1997 –S.Redaelli (CERN) 2003 –B.Bolzon (LAPP) 2007 –M.Warden (Oxford) ~2010 –R. LeBreton (SYMME) ~2012 TolerancesMain beam Quadrupoles Final Focusing Quadrupoles Vertical1 nm > 1 Hz0.1 nm > 4 Hz Horizontal5 nm > 1 Hz5 nm > 4 Hz Active vibration control is not yet a mature technology. Activity should be defined as R&D but with CLIC engineering as objective. It will take time to achieve the final objective but a work plan has been agreed with CDR as an important milestone. Each time a new team starts this study, there is a non negligible “learning period”. Initially, only vertical direction was studied

6 CERN vibration test stand Nanometer linac Stabilisation CLIC small quadrupole stabilised to nanometer level by active damping of natural floor vibration passive active (S.Redaelli 2003) Feasibility already demonstrated : Isolation on commercial TMC table (x10)

7 Cantilever FF stabilisation CERN TMC active table for isolation  The two first resonances entirely rejected  Achieved integrated rms of 0.13nm at 5Hz LAPP active system for resonance rejection Isolation Resonance rejection (L.Brunetti et al, 2007) 2.5m FF Al mock-up Feasibility already demonstrated: compensation of resonances with LAPP feedback (X3)

A.Jeremie MDI - CLIC CDR, May And adding active isolation rms S. Redaelli, CERN 2004 Approach: « Replace » TMC table by a more compact device LAPP option Until now, the isolation function was studied on a TMC commercial active table: almost CLIC specifications but too big! (2.4mx0.9mx0.6m) Feasibility to be demonstrated: isolation on compact device to fit in tight space

9 3 d.o.f. : actuators Relative sensors (more compact) Soft elastomere joint in between Option LAPP: Soft support (joint more for guidance than really « soft ») and active vibration control Rigid: less sensitive to external forces but less broadband damping A.Jeremie MDI - CLIC CDR, May Feasibility to be demonstrated: isolation on compact device to fit in tight space

10 Status: Construction + tests on elastomer A.Jeremie MDI - CLIC CDR, May

11 Sensors that can measure nanometres Absolute velocity/acceleration studied at LAPP: Relative displacement/velocity: Capacitive gauges :Best resolution 10 pm (PI), 0 Hz to several kHz Linear encoders best resolution 1 nm (Heidenhain) Vibrometers (Polytec) ~1nm at 15 Hz Interferometers (SIOS, Renishaw, Attocube) <1 nm at 1 Hz OXFORD MONALISA (laser interferometry) Optical distance meters Compact Straightness Monitors (target 1 nm at 1 Hz) Sub-nanometre measurements CERN test bench : membrane and interferometer ATF2 vibration and vacuum test  Validation  Next: optical test Feasibility to be demonstrated: has to work in magnetic field and radiation environment

Güralp CMG-40T Sensor type: electromagnetic geophone broadband Signal: velocity x,y,z Sensitivity: 1600V/m/s Frequency range: 0,033-50Hz Mass: 7,5kg Radiation: Feedback loop so no Magnetic field: no Feedback loop First resonance 440Hz Temperature sensitivity: 0,6V/10°C Electronic noise measured at >5Hz: 0,05nm Stable calibration A.Jeremie MDI - CLIC CDR, May

Endevco 86 Sensor type: piezoelectric accelerometer Signal: acceleration z Sensitivity: 10V/g Frequency range: 0,01-100Hz but useful from 7Hz Mass: 771g Radiation: piezo OK, but resin? Magnetic field: probably OK but acoustic vibrations? Feedback loop First resonance 370Hz Temperature sensitivity: <1% Electronic noise measured at >5Hz: 0,25nm, >50Hz 0,02nm Stable calibration, flat response Doesn’t like shocks A.Jeremie MDI - CLIC CDR, May

SP500 Sensor type: electrochemical, special electrolyte Signal: velocity Sensitivity: 20000V/m/s Frequency range: 0,016-75Hz Mass: 750g Radiation: no effect around BaBar (don’t know exact conditions) Magnetic field: tested in 1T magnet => same coherence, amplitude? Feedback loop First resonance >200Hz Electronic noise measured at >5Hz: 0,05nm Unstable calibration, response not flat Robust A.Jeremie MDI - CLIC CDR, May

15A.Jeremie MDI - CLIC CDR, May Cantilever option Gauss points option How to integrate with the rest (cantilever or Gauss points)

Preliminary FF calculations just preliminary tests to get a feeling of what is going on…the numbers are not optimized 16 Solid block without coils : 991Hz Solid block with mass of coils : 557Hz Work started with separate coils 2 supports under magnet : 249Hz Cantilever : 125Hz L.Pacquet, G. Deleglise A.Jeremie MDI - CLIC CDR, May Modal analysis and vibration measurements on QD0

17 Test program at LAPP: Currently: tests on a sensor borrowed from micro-epsilon (CS ) on a dedicated test set-up. Have to give back end of this week  Preliminary results show that a nanometre movement can be measured by the sensor Bought a sensor from PI (D-015): Just received!, complete (not quick and dirty like currently on borrowed sensor) for about a month. Then if OK, we will buy 3 more: receive this summer. Then tests on isolation device can start. Study elastomere : shape (recent tests are difficult to interpret, need a better study) and fabrication process: unique piece vs separate rings) Optimise Absolute sensor position Optimise Passive material position Work on FF magnet. A.Jeremie MDI - CLIC CDR, May Difficult before CDR!