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CLIC MDI

CLIC MDI. Final Focusing Magnet Stabilisation Studies. Recent History. Conventional Facility Design for NLC · Stanford Linear Accelerator Center, March 10 to 28, 2003 CARE/ELAN meeting @ CERN November 23 - 25 2005. CLIC07 Workshop, 16-18 October 2007

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CLIC MDI

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  1. CLIC MDI Final Focusing Magnet Stabilisation Studies

  2. Recent History • Conventional Facility Design for NLC · Stanford Linear Accelerator Center, March 10 to 28, 2003 • CARE/ELAN meeting @ CERN November 23 - 25 2005. • CLIC07 Workshop, 16-18 October 2007 • Stabilisationday at CERN, March 18 • Nanobeam2008 (Novosibirsk, 27 May 2008) • EUROTeV Scientific Workshop at Uppsala,August 2008 Detlef Swoboda @ CLIC MDI working group

  3. (Some) Literature • Preliminary Results of the Ground Vibration Measurements at Potential Linear Collider Sites and Reference Places (2003 SLAC) • Vibration stabilization for the final focus magnet of a future linear collider (November 2005) • Status report on active stabilisation of a linear collider final focus quadrupole mock-up (2006) • The stabilisation of final focus system (December 2007 Pramana) • US Particle Accelerator School, January 22-26, 2007 in Houston, Texas • Status of Mechanical Stabilization (2008 Uppsala) • Vibration stabilization for a cantilever magnet prototype at the sub-nanometer scale (July 2008) • Study of vibrations and stabilization at the sub-nanometre scale for clic final doublets (2008) • CTF3 module and CLIC Final Doublet stabilization (??) Detlef Swoboda @ CLIC MDI working group

  4. Global requirements magnets can be constructed, supported, and monitored so as to meet alignment tolerances Detlef Swoboda @ CLIC MDI working group

  5. Scope of FFS CLIC LinearCollider (~2019): Detector Interaction point 2m50 Final doublets in cantilever Vertical beam size at the interaction point: 1nm Tolerance of vertical relative positioningbetween the twobeamsto ensure the collision withonly 2% of luminosityloss: 1/10nm Below 5Hz: Beam position control withdeflectormagnets efficient Above 5Hz: Need to control relative motion between final doublets Detlef Swoboda @ CLIC MDI working group

  6. FF doublet (NLC ZDR) Detlef Swoboda @ CLIC MDI working group

  7. Final Focusing f1 f2 (=L*) Use telescope optics to demagnify beam by factorM = f1/f2 typically f2= L* The final doublet FD requires magnets with very high quadrupole gradient in the range of ~250 Tesla/m  superconducting or permanent magnet technology. Detlef Swoboda @ CLIC MDI working group

  8. Chromaticity correction • Minimization of chromatic distortions: factors that influence the solutions to this problem: • a reduction in the momentum spread (not always feasible) would reduce the magnitude of the problem • The chromatic distortion of a FFS lattice is a function of the distance L*. The closer and stronger the lens the smaller is the distortion. • Sextupoles in combination with dipoles (provide dispersion) can be used to cancel chromaticity. Sextupoles introduced as pairs, separated by a –I transform do not generate second order geometric aberrations. However the dipoles introduce emittance growth and energy spread due to synchrotron radiation. Serious constraint. • FF design  Balance between these competing effects Detlef Swoboda @ CLIC MDI working group

  9. Novel local chromaticity correction scheme P.Raimondi, A.Seryi, originally NLC FF and now adopted by all LC designs. Detlef Swoboda @ CLIC MDI working group

  10. Elements of LC Final Focus System Summary In Linear Colliders, nanometer size beams are obtained by: • Final Quadrupole Doublet telescopic system • FD Collateral effects: generate strong chromatic aberrations • Sextupoles to correct FD chromatic aberrations • SEXT collateral effects: generate geometric aberrations • Sextupoles located at beginning of -I transformer (or equivalent transform) then correct geometric aberrations • Dipoles to supply dispersion for Sextupoles correction • BEND collateral effects: generate synchrotron radiation Detlef Swoboda @ CLIC MDI working group

  11. STUDY OF SOME OPTIONS FOR THE CLIC FINAL FOCUSINGQUADRUPOLE CLIC Note 506 M. Aleksa, S. Russenschuck Detlef Swoboda @ CLIC MDI working group

  12. Permanent Magnets Detlef Swoboda @ CLIC MDI working group

  13. Permanent Quad Concepts • A new style of permanent magnet multipole has been described. • achieve linear strength and centerline tuning at the micron level by radially retracting the appropriate magnet(s). • Magnet position accuracies are modest and should be easily achievable with standard linear encoders Rotatable PM (Nd-Fe-B) Block to Adjust Field (+/- 10%) PM (Strontium Ferrite) Section Steel Pole Pieces (Flux Return Steel Not Shown) Detlef Swoboda @ CLIC MDI working group

  14. The first prototype of “superstrong” Permanent Magnet Quad. Cut plane view Soft iron PM Axial view PHOTO Integrated strength GL=28.5T (29.7T by calc.) magnet size.f10cm Bore f1.4cm Field gradient is about 300T/m Detlef Swoboda @ CLIC MDI working group

  15. Double Ring Structure –Adjustable PMQ- • High gradient  heat load The double ring structure PMQ is split into inner ring and outer ring. Only the outer ring is rotated 90around the beam axis to vary the focal strength. Detlef Swoboda @ CLIC MDI working group

  16. Options for Various L* & X’ing Angles NBS (For Head on) SBS (For 2mrad) MBS (For 7mrad) LBS(2nd prototype)(For 20mrad) NBS=No Beam Separation, SBS=Small Beam SeparationMBS=Medium Beam Separation, LBS=Large Beam Separation Detlef Swoboda @ CLIC MDI working group

  17. SC back leg coil SC Magnets Coil dominated Detlef Swoboda @ CLIC MDI working group

  18. General Environment The CLIC luminosity performance critically depends on the main linac quadrupole vertical stability (<1nm @ 1Hz) and the final doublet stability (<0.1nm @ 4 Hz) in noisy site Linac 1.3nm S.Redaelli’s PhD 2003 FF 0.2nm Measurement of the quadrupole vibrations on active table in vertical direction compared to linac and Final Focus (FF) tolerances at 4Hz (in 2003) 4 Hz Detlef Swoboda @ CLIC MDI working group

  19. Cultural Noise At SLS at PSI, quad vs ground: some peaks correlate with beam jitter, some can be explained by He compressors or beam infrastructure (seen also in beam), but some peaks are due to girder resonances • Stable or damped support vital, but test in accelerator environment essential R.Assmann et al CERN-AB-2004-074 Detlef Swoboda @ CLIC MDI working group

  20. Why test in an accelerator environment? B.Bkalov et al PHY REV Spec Topics- Accel and beams 1 031001 (1998) Tevatron integrated rms in deep tunnel: at 0.1 Hz, 0.3micron and falls off with increasing frequency, there are strong peaks correlated with the beam frequency (magnet distortion during running cycle) below 5 Hz and above 20 Hz, the equipment in tunnel is noisier than surface at night. Also very strong correlation with He liquefier plant. In LEP tunnel, above 4 Hz, vibration goes from 0.2 nm to 20nm when beam equipment is turned on.(V.E.Balakin et al CERN-SL-93-30-RFL (1993). Ramila Amirikas and DESY team presented (at LCWS 07) some site measurements Fermilab surface 32 nm at 1Hz, CERN 22 nm at 1Hz Fermilab tunnel 3nm LHC tunnel 2nm Did some calculations to remove the 1/f and to keep only cultural noise: Quiet sites below 10nm, medium below 30nm, and noisy sites above 50nm. Detlef Swoboda @ CLIC MDI working group

  21. State of the art inertial sensors • NI PCI-6052 Multifunction DAQ Fast card Low noise card • Compatible Matlab/Simulink (Softwares used for the algorithm) nm stabilisation equipment exists Detlef Swoboda @ CLIC MDI working group

  22. Active isolation from the ground: commercial system Presentation of the STACIS commercial system Isolator Honeycomb table Controller :Control actuators from geophone data • Isolator: • Elastomer: Passive isolation • 1 geophone / 1 vertical actuator • 2 geophones / 2 horizontal actuators Active isolation Detlef Swoboda @ CLIC MDI working group

  23. Active compensation The prototype • The large prototype and its instrumentation : 2.5 m long • Actuators used for the active control of vibration : • Force = 19.3 N • Maximal displacement = 27,8 μm • Resolution = 0,28 nm - A stacking of PZT patches - Detlef Swoboda @ CLIC MDI working group

  24. Vibration study of a cantilever beam at highfrequencies • Ground motion: decreases with frequency Studiesfocuseduntilnow on highest motions (below 300Hz) Team of DESY Waves on coasts Effect of the earth Cultural noise • Vibration study of a cantilever beam for f>300Hz • Amplification at resonances • Impact of acoustic noise Detlef Swoboda @ CLIC MDI working group

  25. Tests with the large prototype: quiet room integrated displacement RMS (with active table ON) 1 nm Actuator electronic noise at 50 Hz Detlef Swoboda @ CLIC MDI working group

  26. Active control CIM Tests with the large prototype • Results : integrated displacement RMS Detlef Swoboda @ CLIC MDI working group

  27. Conclusion and future prospects • Vibration sensors and instrumentation • Ground motion measurements from low to high frequencies (0.1Hz  2000Hz) • Measurement chain found for active rejection of CLIC final doublets vibrations (1/10nm for f>5Hz) • Collaboration with PMD Scientific company to test new electrochemical sensors tending toward the final specification of CLIC • Test of small capacitive sensors with 0.1nm resolution (P75211C of PI) • Vibration study of a canteliver beam at high frequencies (>300Hz) • High impact of acoustic noise up to at least 1000Hz for CLIC FD • Measurements to perform on canteliver magnets in an operating accelerator site Detlef Swoboda @ CLIC MDI working group

  28. Conclusion and future prospects • Active stabilization of a canteliver beam down to the sub-nanometre level above 5Hz • Feasibility of active isolation from the ground proven • Active rejection feasibility of resonances proven • On-going study: multi-sensors multi-actuators system in order to stabilize the beam all along its length • Stabilization to do on a more complex structure closer to the FD design Simulations give us information about optimal location of sensors and actuators and their number Simulations willallow us to follow the evolution of final doublets design Detlef Swoboda @ CLIC MDI working group

  29. PM SC RM RM Beam delivery system • Magnet Technology IP • IP concept Crab XP 1 Detlef Swoboda @ CLIC MDI working group

  30. Summary (1) • Vibration & stabilization • Several studies and R&D • Passive damping & active compensation (table) • Modeling & active compensation (cantilever support) • Commercial equipment for controlled environment like IC production in accelerator noise > 10 x. • Suspension vs. support? • FF Quad magnet technology • High gradient ( N x 100 T/m) requires permanent/SC technology • Combination of both types? Detlef Swoboda @ CLIC MDI working group

  31. Summary (2) • IP layout • Push-pull vs. 2nd IP? • Need to define strategy, resources, timescale. Detlef Swoboda @ CLIC MDI working group

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