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

Overview Introduction Hadron colliders Lepton-hadron e+e- linear colliders e+e- ring colliders  colliders Conclusions

Basic LC IR Drivers Bunch Structure: Beam-beam effects Small spot sizes: TESLA-500NLC-500 BB 337 ns2.8ns/1.4ns NBNB /190 f5 Hz120 Hz CC 0 mrad20 mrad xx 550 nm245 nm yy 5 nm2.7 nm N 2.0 x x zz 300  m110  m  Crossing Angle & Feedback Design  IP Backgrounds & Pinch Enhancement  Control position & motion of final quads and/or the beam

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

e+,e- pairs from beams.  interactions are the most important background # scales w/ L 2.5-5x10 9 /sec B SOL, L*,& Masks

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

NLC Detector Masking Plan View w/ 20mrad X-angle 32 mrad 30 mrad Large Det.- 3 TSilicon Det.- 3 T

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

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

TESLA SC Final Doublet Quads Mature LHC=based Design QD0: L=2.7m G=250 T/m Aperture=24mm QF1: L=1.0m

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

Extraction and Diagnostics Handling the Disrupted Beam NLC Post-IP Diagnostics Common ,e dump TESLA Pre-IP Diagnostics Separate  & e dumps

Colliding Small Beam Spots at the IP 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  y ~ 3-5 nm  y =  y /(4-10) ~ nm Q1 e+ e- Relative Motion of two final lenses

Intra-train Feedback based on beam-beam deflection at TESLA In 90 bunches and  L < 10%, bunches are controlled to 0.1  y D y ~25  ~0.1  ~0.5nm sensitivity

Very Fast Intra-train IP Feedback at NLC limits jitter-induced  L Concept Performance 5  Initial Offset (13 nm) Design 40ns Latency Y IP (nm)

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

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

 Collider IR Laser Development Fusion program-funded “Mercury” laser project applicable to  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  e collisions have been developed and will soon be tested. Optics and IP parameters improved performance for  collisions

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

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

8 May 1999 Matching Laser Output to Accelerator Bunch Structure Known Technology –  specific development planned

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

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

 Collider IR Shielding Designs tuned for 100 GeV, 500 GeV, and 4 TeV

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  Laser & IR Optics now available and give program real credibility

NLC/TESLA Beam-Beam Comparison NLC500TESLA500 DyDy 1425  nn bb 4.6%3.2% HDHD #pairs/ sec 2.5E94.7E9 Larger  z 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

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