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 7 2010

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?)

4Andrea JEREMIE

Example of spectral analysis of different disturbance sources

Acoustic disturbance :

Amplified by the structure itself : the eigenfrequencies

Ground motion :

Seismic motion

Cultural noiseA 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:

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Some commentsSeveral PhDs:

– C.Montag (DESY) 1997 – S.Redaelli (CERN) 2003– B.Bolzon (LAPP) 2007– M.Warden (Oxford) ~2010– R. LeBreton (SYMME) ~2012

Tolerances Main beam Quadrupoles

Final Focusing Quadrupoles

Vertical 1 nm > 1 Hz 0.1 nm > 4 Hz

Horizontal 5 nm > 1 Hz 5 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

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CERN vibration test stand

Nanometer linac StabilisationCLIC small quadrupole stabilised

to nanometer level by activedamping of natural floor vibration

passive

active

(S.Redaelli 2003)

Feasibility already demonstrated : Isolation on commercial TMC table (x10)

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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 7 2010 8

And adding active isolation

rms

S. Redaelli, CERN 2004

Approach: « Replace » TMC table by a more compact device

LAPP optionUntil 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

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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 7 2010

Feasibility to be demonstrated: isolation on compact device to fit in tight space

A.Jeremie MDI - CLIC CDR, May 7 2010 10

Status: Construction + tests on elastomer

A.Jeremie MDI - CLIC CDR, May 7 2010 11

Sensors that can measure nanometresAbsolute 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 metersCompact Straightness Monitors (target 1 nm at 1 Hz)

Sub-nanometre measurements

CERN test bench : membrane and interferometer

ATF2 vibration and vacuum testÞ ValidationÞ Next: optical

test

Feasibility to be demonstrated: has to work in magnetic field and radiation environment

Güralp CMG-40TSensor type: electromagnetic geophone broadbandSignal: velocity x,y,zSensitivity: 1600V/m/sFrequency range: 0,033-50HzMass: 7,5kgRadiation: Feedback loop so noMagnetic field: noFeedback loopFirst resonance 440HzTemperature sensitivity: 0,6V/10°CElectronic noise measured at >5Hz: 0,05nmStable calibration

A.Jeremie MDI - CLIC CDR, May 7 2010 12

Endevco 86Sensor type: piezoelectric accelerometerSignal: acceleration zSensitivity: 10V/gFrequency range: 0,01-100Hz but useful from 7HzMass: 771gRadiation: piezo OK, but resin?Magnetic field: probably OK but acoustic vibrations?Feedback loopFirst resonance 370HzTemperature sensitivity: <1%Electronic noise measured at >5Hz: 0,25nm, >50Hz 0,02nmStable calibration, flat responseDoesn’t like shocks

A.Jeremie MDI - CLIC CDR, May 7 2010 13

SP500Sensor type: electrochemical, special electrolyteSignal: velocitySensitivity: 20000V/m/sFrequency range: 0,016-75HzMass: 750gRadiation: no effect around BaBar (don’t know exact conditions)Magnetic field: tested in 1T magnet => same coherence, amplitude? Feedback loopFirst resonance >200HzElectronic noise measured at >5Hz: 0,05nmUnstable calibration, response not flatRobust

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Cantilever option

Gauss points option

How to integrate with the rest (cantilever or Gauss points)

Preliminary FF calculationsjust preliminary tests to get a feeling of what is going on…the numbers are not optimized

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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 7 2010

Modal analysis and vibration measurements on QD0

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Test program at LAPP:

Currently: tests on a sensor borrowed from micro-epsilon (CS601-0.05) on a dedicated test set-up.Have to give back end of this weekÞ 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 7 2010

Difficult before CDR!