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Interaction Regions Working Group (T1)

Interaction Regions Working Group (T1). Final Report T.Markiewicz, F.Pilat. Snowmass 2001. Plenary Session Snowmass, July 19. Overview. Introduction Hadron colliders Lepton-hadron e+e- linear colliders e+e- ring colliders m-m colliders Conclusions. Basic LC IR Drivers.

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Interaction Regions Working Group (T1)

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  1. Interaction Regions Working Group (T1) Final Report T.Markiewicz, F.Pilat Snowmass 2001 Plenary Session Snowmass, July 19

  2. Overview • Introduction • Hadron colliders • Lepton-hadron • e+e- linear colliders • e+e- ring colliders • m-m colliders • Conclusions

  3. Basic LC IR Drivers • Bunch Structure: • Beam-beam effects • Small spot sizes: Crossing Angle & Feedback Design IP Backgrounds & Pinch Enhancement Control position & motion of final quads and/or the beam

  4. Backgrounds and IR Layouts • Most important background is the incoherent production of e+e- pairs. • # pairs scales with luminosity and is ~equal for both designs. • Detector occupancies depend on machine bunch structure and relevant readout time • GEANT and FLUKA based simulations indicated that in both cases occupancies are acceptable and the CCD-based vertex detector lifetime is some number of years. • IR Designs & Magnet Technologies • Differ due to the crossing angle, magnet technology choice, and separate extraction line in the case of the NLC • Similar in the use of tungsten shielding, instrumented masks, and low Z material to absorb low energy charged and neutral secondary backgrounds

  5. e+,e- pairs from beams. gg interactionsare the most important background # scales w/ L 2.5-5x109/sec BSOL, L*,& Masks

  6. TESLA IR(Instr. W Masks, Pair-LumMon, Low Z)

  7. NLC Detector MaskingPlan View w/ 20mrad X-angle Large Det.- 3 T Silicon Det.- 3 T 30 mrad 32 mrad

  8. JLC IR8 mrad Design Elevation View • Iron magnet in a SC Compensating magnet • 8 mrad crossing angle • Extract beam through coil pocket • Vibration suppression through support tube

  9. Detector Occupancies are Acceptablefn(bunch structure, integration time) TESLA VXD Hits/BX vs. Radius LCD=L2 Hit Density/Train in VXD &TPC vs. Radius TESLA #g/BX in TPC vs. z

  10. TESLA SC Final Doublet QuadsMature LHC=based Design • QD0: • L=2.7m • G=250 T/m • Aperture=24mm • QF1: • L=1.0m

  11. NLC Final Doublet QuadsCompact, stiff, connection free Permanent Magnet Option EXT QD Carbon fiber stiffener nm-mover FFTB style cam movers Cantilevered support tube T2: Compact SC (HERA-style)

  12. Extraction and DiagnosticsHandling the Disrupted Beam NLC Post-IP Diagnostics Common g,e dump TESLA Pre-IP Diagnostics Separate g & e dumps

  13. Colliding Small Beam Spots at the IP Q1 Q1 Relative Motion of two final lenses e+ e- sy ~ 3-5 nm Dy = sy/(4-10) ~ 0.5-1 nm • Control position & motion of final quads and/or position of the beam to achieve/maintain collisions • PASSIVE COMPLIANCE: Get a seismically quiet site, don’t screw it up (pumps, compressors, fluids), engineer the quad/detector interface • FEEDBACK: Between bunch trains & Within bunch trains • SENSE MOTION & CORRECT MAGNETS or BEAMS

  14. Intra-train Feedback based on beam-beam deflection at TESLA Dy~25  ~0.1s~0.5nmsensitivity In 90 bunches and DL < 10%, bunches are controlled to 0.1sy

  15. Very Fast Intra-train IP Feedback at NLC limits jitter-induced DL Concept Design Performance 5 s Initial Offset (13 nm) YIP (nm) 40ns Latency

  16. R&D on Inertial Stabilization to Suppress Jitter at NLC Block with Accelerometers/ Geophones & Electrostatic Pushers x10-100 Jitter Suppression in Frequency Range of Interest

  17. R&D on Interferometers to Stabilize Quads w.r.to Tunnel Sub-nm resolution measuring fringes with photodiodes  drive piezos in closed loop Measured Displacement over 100 seconds rms = 0.2nm UBC Setup

  18. gg Collider IR Laser Development • Fusion program-funded “Mercury” laser project applicable to gg project is under construction • Conceptual designs to take the output of the laser and to match it to the time structure required for either the NLC or TESLA are underway IR Optical designs • to provide the ge collisions have been developed and will soon be tested. Optics and IP parameters • improved performance for gg collisions

  19. Mercury power amp Mercury power amp Mercury power amp LLNL 10Hz -100J “MERCURY” Fusion Program Laser IS Prototype for gg Collider g-g laser system architecture: CPA front end seeds 12 Mercury power amplifiers Mode-locked oscillator Spectral shaper Stretcher OP-CPA preamp 0.5 J 3 ns 120 Hz 12- 100 J power amplifiers Optics: Combiner, splitters Beam splitters 100 J macropulse: 100X 2ps micropulses 120 Hz Grating compressor

  20. Diode pulsers Front end Gas-cooled amplifier head Pump delivery Injection multi-pass spatial filter

  21. Matching Laser Output to Accelerator Bunch StructureKnown Technology – gg specific development planned 8 May 1999

  22. Large Diameter gg Annular Optics Engineered Performance Tests Planned Out of the way of input beam & beam-beam debris

  23. Circular e+e- IRs • HOM • SR • SR Masks • Beam Tails • Orbit Compensation

  24. mm Collider IR Shielding Designs tuned for 100 GeV, 500 GeV, and 4 TeV

  25. Conclusions Many IR design issues are common across different types of machines The proposed designs for LC IRs look more similar than different, are fairly well advanced, and have active R&D programs Viable solutions to gg Laser & IR Optics now available and give program real credibility

  26. NLC/TESLA Beam-Beam Comparison • Larger sz for TESLA • More time for disruption • larger luminosity enhancement • more sensitivity to jitter • Lower charge density • lower energy photons • Real results come from beam-beam sim. (Guinea-Pig/CAIN) and GEANT3/FLUKA

  27. Magnet Technology Choices Permanent Magnets (NLC) • Compact, stiff, few external connections, no fringe field to affect extracted beam • Adjustment more difficult Superconducting (TESLA) • Adjustable, big bore • Massive, not stiff, not compact, external connections Iron (JLC) • Adjustable, familiar • Massive, shielded from detector solenoid, extraction through coil pocket

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