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LiCAS Project Status

LiCAS Project Status. Edward Botcherby, Richard Bingham, Paul Coe, John Green, Grzegorz Grzelak , Ankush Mitra, John Nixon, Armin Reichold, Roman Walczak. (LCUK meeting, QMUL, 5 FEB ’03). Outline. Latest News: LiCAS is now PPRP founded project: 50 k£ (+6k£ travel)

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LiCAS Project Status

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  1. LiCAS Project Status Edward Botcherby, Richard Bingham, Paul Coe, John Green, Grzegorz Grzelak, Ankush Mitra, John Nixon, Armin Reichold, Roman Walczak (LCUK meeting, QMUL, 5 FEB ’03) LiCAS Project Status, LCUK Meeting

  2. Outline • Latest News: LiCAS is now PPRP founded project: 50 k£ (+6k£ travel) • Linear Collider Alignment Problem (TESLA) • Proposed Survey Technology • LiCAS Implementation • FSI: Frequency Scanning Interferometry • SM: Straightness Monitor • Recent Progress (FSI,SM, Simulations) • Conclusions/Plans LiCAS Project Status, LCUK Meeting

  3. Survey and Alignment Problem • Tight space (~1m wide) • Many beamlines • Curved tunnel sections • Significant slopes possible • Some sections follows geoid, others are geometrically straight • Temperature and pressure gradients in tunnel • Electrically noisy environment • Induced radiation • Automated measurement needed LiCAS Project Status, LCUK Meeting

  4. Survey and Alignment Problem • TESLA Specification: • 200 mm vertical over 600 meters (=betatron wavelength) • Survey procedure is needed during: • Tunnel construction • Installation of collider components • Accelerator maintenance/repairs • Open air survey too slow and too inaccurate • Need new instrument that matches requirements • ATLAS and ZEUS technologies: FSI and SM developed in Oxford applicable to this problem LiCAS Project Status, LCUK Meeting

  5. Generic Solution • Collider has large number of marker (many lines) • Collider markers are irregular (not good for automation) • Tunnel needs to be surveyed long before collider is installed • Use a two step process • Survey regularly spaced markers in tunnel wall: LiCAS job! • Survey collider components against markers: Second more simple instrument LiCAS Project Status, LCUK Meeting

  6. SM beam internal FSI wall markers external FSI LiCAS technology also applicable to second instrument ! collider component Survey Implementation Tunnel Wall Reconstructed tunnel shapes (relative co-ordinates)

  7. straightness monitors FSI-distance measurements LiCAS Implementation • Mechanical concept of the train developed at DESY • Internal Laser lines (FSI,SM) operate in vacuum • Scalable laser technology (EDFA & TELECOM style infrared lasers) • Prototype @DESY in dedicated test tunnel • Advantages: • Suitable for TESLA and NLC • Operates in inclined and curved tunnels • Higher intrinsic resolution and faster survey • cheaper LiCAS Project Status, LCUK Meeting

  8. IRef time Change of phase: DFRef IGLI time FSI Principle • Interferometric length measurement system • Originally developed at Oxfordfor online alignment of ATLAS SCT tracker • Required measurement precision is 1mm over 5m • Two lasers with opposite tuning direction reduce drift sensitivity (not shown) Tunable Laser Reference Interferometer Length = L Grid Line Interferometer (GLI) Length = D Change of phase: DFGLI LiCAS Project Status, LCUK Meeting

  9. FSI System Amplitude Modulation @ f1 C-Band Amplifier (1520-1570) Laser 1 f1 L-Band Amplifier (1572-1630) Laser 2 f2 Amplitude Modulation @ f2 Reference Interferometer Splitter Tree piezo detector Quill Demodulator @ f1 , F1 Amplifier Amplifier ADC 2MHz ADC 2MHZ Detectors Demodulator @ f2 , F1 Retro Reflector Buffer Memory GLI USB-2 Readout Amplifier ADC20MHZ Demodulator @ f2 , F1 Readout Board LiCAS Project Status, LCUK Meeting

  10. New Lasers • increased continuous, mode hop free fine tuning range by factor 300 (0.24nm to 130nm) or (100GHz @ 850nm to 16THz @ 1500nm) • increased total tuning range by factor 8 from 16nm to 130nm • increase fine tuning speed by factor 3000 (100GHz/min to 5 THz/sec) or (0.24nm/sec @ 850nm to 40nm/sec @ 1500nm) • Erbium doped fibre amplifiers as inexpensive, scalable sources of laser power (100 mW per EDFA) • telecommunication fibres and accessories much cheaper than components at 850nm LiCAS Project Status, LCUK Meeting

  11. Recent Developments • Selected and commissioned LiCAS laser • Set-up first LiCAS FSI interferometer • Simultaneous transmission and readout of two lasers in the same interferometer • Designed two FSI collimation systems (reflective and refractive) • Designed two collimation systems for SM and implemented one • Designed two reduction optics for SM and implemented one • Complete demonstration prototype of SM constructed (laser, collimation optic, reduction optic, camera, frame grabber, software) • Two optical simulation packages (OPTICA, ZEMAX) • Geometrical simulations of LiCAS performances • Fully equipped laboratory from online auctions of telecoms insolvencies LiCAS Project Status, LCUK Meeting

  12. 15% mod. Volts 15% mod. Time Volts Time Recent Developments • Amplitude Modulation on FSI fringe • @ 40 & 80 kHz (now) 0.5 & 1MHz (later) • High Pass Filter • FSI fringe stored as amplitude on • Carrier (a’la AM radio) • Demodulation reproduces FSI Fringes LiCAS Project Status, LCUK Meeting

  13. l2 wavelength l1 M1 time Amplitude Modulation @ f1 M2 Laser 1 Volts Laser 2 Demodulator @ f1 , F1 Detector Amplitude Modulation @ f2 l2 time wavelength Volts Demodulator @ f2 , F1 l0 time time Recent Developments t0 t1 f1 f2 t0 t1 LiCAS Project Status, LCUK Meeting

  14. CCD 1 2) CCD 2 y y z z Straightness Monitor Two beams shown • Two parallel laser beams • Low coherence length diode laser to avoid interference on CCD • Two possible splitter configurations 1) • Measure transverse translations • Need 1mm precision over length of train • 1:10 demagnification optics to increase dynamic range  0.1 mm CCD resolution • Measure rotations around x and y axis One beam shown in Configuration 1) Rotation: Spots move opposite directions Translation: Spots move same direction

  15. y y z x Straightness Monitors Use two parallel beams to measure rotation about z-axis SM beams coming out of the screen Image of beam spots observed on CCD Camera LiCAS Project Status, LCUK Meeting

  16. SM: Results Basic SM optics has been set-up. Fitted Gaussian to camera image Camera looking at low-coherence laser LiCAS Project Status, LCUK Meeting

  17. Simulations: single train without clinometer (SIMULGEO package developed by L. Brunel for CMS) • FSI resolution: 1 mm • SM CCD resolution 0.01 mm (unrealistic !) • Problem: weak measurement of rotation around z-axis  small separation between two beams on CCD LiCAS Project Status, LCUK Meeting

  18. Simulations: single train + 1-Axis Clinometer • FSI resolution 1 mm • SM CCD resolution 0.1 mm • Clinometer resolution 1 mrad •  much better precision for Y-coordinate of wall markers LiCAS Project Status, LCUK Meeting

  19. Hard Requirements  need good point accuracy ! Simulation over 600 m  input for beam dynamics simulations LiCAS Project Status, LCUK Meeting

  20. Conclusions/Plans • Modern Survey Approach • Using the latest achievements developed for ATLAS and ZEUS • General Purpose Alignment System (TESLA/FEL, NLC, …) • Cost effective solution (TELECOM lasers, fibre amplifiers) • New LAB in Oxford, many new developments in progress • Man Power: 6 FTE in 2003 • Collaboration with DESY: • Test the prototype in dedicated tunnel in DESY • First application of the system: X-FEL (2005 -> in 2 years !) LiCAS Project Status, LCUK Meeting

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