CLIC FF where we stand, where are we going?

1. CLIC FF where we stand,where are we going? A.Jeremie

2. Short summary • Achieved performance • Current work • Future plans Schedule with strong incentive from CDR in 2010! FF part of both the MDI WG and the Stabilisation WG => liaison A.Jeremie • Comments: • Several PhDs: • S.Redaelli (CERN) 2003 • B.Bolzon (LAPP) 2007 • M.Warden (Oxford) ~2010 • R. LeBreton (SYMME) ~2011 • Each time a new team starts this study, there is a non negligible “learning period”.

3. L.Brunetti et al (EPAC/Genova 2008) Achieved performance LAPP active system for resonance rejection CERN TMC active table for isolation • The two first resonances entirely rejected • Achieved integrated rms of 0.13nm at 5Hz

4. Current work Replace big stabilisation table by a compact passive+active stabilisation system Active system Passive system Instrumentation study (sensors and actuators)

5. Ex : force (actuator) applied to a point Current work Simulations Feedback development • Different strategies studied: • A knowledge only at strategic points • A local model for the disturbances amplified by eigenfrequencies. • A complete model FF magnet design Evgeny Solodko

6. FF stabilisation • Performance issue: if not sufficent => show stopper • Cost issue: only one pair (QD0 and QF1) on each side of the detector. In principle, not a big cost issue. However, very stringent specs, so costly high performance components.

7. FF needs towards feasibility demonstration • Remember: subnanometer stabilisation at 5Hz already demonstrated in laboratory on a cantilever prototype. Is this sufficient to convince that we can do it? • What is missing?

8. What is needed? • Reliable sensors (small, rad hard, magnetic field hard, low frequency range, nm range). So far only coil sensors used and the molecular sensors don’t seem to be stable in time. Geophones and accelerometers: do we need displacement sensors? Where should they go? • Reliable actuators: piezo stacks (Cedrat, PI) OK. Still to confirm weight range and displacement range. • Feedback algorithm: cantilever compensation demonstrated for one sensors/one actuator. Is this enough? Study new algorithms with mutlisensors/multiactuators, complete structure model, compare co localised and distributed. • Demonstration done on big TMC table. Replace the isolation function by a more compact device. Commercial? Are there weight and configuration issues (how can a small device hold a cantilever?). • Understand what influences tolerances (coherence, supports…)

9. FF needs towards feasibility demonstration • Can we build a PM FF? How stable can a long structure made out of short pieces be? Simulations. • How much space is there for the FF? What shape with the spent beam? Aperture? Is FF different for 500GeV? • How can it be supported inside the detector? Are we considering a Push-Pull scenario? A study to be done • Cantilever on detector • Cantilever from tunnel • Multifeet from detector • Cantilever from ground (height!!!) • Suspended from detector • Suspended from ceiling (correlation possible for both QD0?) • Common girder through detector… • Need an in depth study with detector conception. • A detector can never be built with the right vibration tolerances!

10. Integration for the Push-Pull 17 m 8.6 m

11. Longer L* CLIC08 • Study prompted by the CLIC FD stability challenge (< 0.2nm) • Double the L* and place FD on a stable floor • Initial study show that L*=8m optics is possible (CLIC08 workshop) • Some (maybe tolerable) impact on luminosity is still unavoidable

12. FF needs towards feasibility demonstration • Can we build a PM FF? How stable can a long structure made out of short pieces be? Simulations. • How much space is there for the FF? What shape with the spent beam? Aperture? • How can it be supported inside the detector? Are we considering a Push-Pull scenario? A study to be done • Cantilever on detector • Cantilever from tunnel • Multifeet from detector • Cantilever from ground (height!!!) • Suspended from detector • Suspended from ceiling (correlation possible for both QD0?) • Common girder through detector • Need an in depth study with detector conception • A detector can never be built with the right vibration tolerances! • Would the FF magnet be simpler for L*=8m (without the spent beam in the way)? What if we only keep the L*=8m for the first stabilisation studies (at least until the CDR is over)?

13. prototypes • Short FF magnet 2010: what can be learned for stabilisation purposes? Pinpoint some sources. Measure with different cooling flows: air, laminate, turbulent. • Use the cantilever prototype for further studies?

14. Accelerator environment? • Module 104 studies in CLEX: 2010 • Electron beam studies (CESR TA and PSI): 2009-2010 • Can we learn from the new FDs in ATF2: 2013? • Active stabilisation needed? Learn from the study. • Vibration sources different • Optics with longer magnet similar? • Is ATF2 going to use both technologies?

15. Summary of actions needed Items covered by MB stabilisation studies Those needing extra work • Reliable sensors • Reliable actuators • Feedback algorithm • Replace the isolation function by a more compact device. • Can we build a PM FF? How stable can a long structure made out of short pieces be? Simulations. • How much space is there for the FF? What shape with the spent beam? • How can FF be supported? • Detector conception. • Prototypes • Behaviour of magnet (simulations) • Accelerator environment? How does this fit with the CDR? MDI-FF review proposed for December 2009-January 2010