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Beam Delivery System Review of RDR(draft) 1.Overview 2.Beam parameters 3.System description 3.1 diagnostic, tune-up dump, machine protection 3.1.1 MPS collimation 3.1.2 Skew correction 3.1.3 Emittance diagnostcs 3.1.4 Polarimeter and energy diagnostics 3.1.5 Tune-up and emergency extraction system 3.2 Collimation system 3.2.1 Muon suppression 3.2.2 Halo power handling 3.2.3 Tail-folding octupoles 3.3 Final focus 3.4 IR design and integration to detector 3.5 Extraction line 4.Accelerator components 4.1 Crab cavity system 4.2 Feedback system and stability 4.2.1 Train-by-train feedback 4.2.2 Intra-train IP position and angle feedback 4.2.3 Luminosity feedback 4.2.4 BDS entrance feedback( ‘train-straightener’) 4.2.5 Hardware implementation for intra-train feedbacks 4.3 Energy, luminosity and polarization measurements 4.3.1 Energy measurements 4.3.2 Luminosity measurements 4.3.3 Polarization measurements 4.4 Beam dumps and collimators 4.5 BDS magnets 4.5.1 BDS magnets: tail-folding octupoles 4.6 Vacuum system 4.6.1 Wakes in vacuum system 4.6.2 Beam-gas scattering 4.6.3 Vacuum system design 4.7 IR arrangements for two detectors 4.8 Diagnostic and correction devices RDR contents S.Kuroda
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1.Overview Single IP(14mrad) and push-pull detector measure the linac beam and match it into the final focus; protect the beamline and detector against mis-steered beams from the main linacs; remove any large amplitude particles (beam-halo) from the linac to minimize background in the detectors; measure and monitor the key physics parameters such as energy and polarization before and after the collisions; Squeeze beam at IP to x=639nm, y=6.7nm RDR
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IR 14 mrad 14 mrad ILC FF9 hybrid (x 2) 14 mrad (L* = 5.5 m) dump lines detector pit: 25 m (Z) × 110 m (X) e-e+ hybrid “BSY” (x 2) 2226 m ΔZ ~ -650 m w.r.t. ILC2006c M.Woodley
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2.Beam Parameters RDR
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3.System Description polarimeter skew correction / emittance diagnostic MPS coll betatron collimation fast sweepers tuneup dump septa fast kickers energy collimation β-match energy spectrometer final transformer final doublet IP energy spectrometer polarimeter fast sweepers primary dump Main Linac ILC2006e electron BDS schematic energy collimation M.Woodley
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3.1 Diagnostic, Tune-up Dump, Machine protection polarimeter skew correction / emittance diagnostic MPS coll β-match Main Linac betatron collimation extraction angle = 0.837 mrad L B =2.4 m (×3) ΔL BB = 0.3 m Compton IP 250 GeV x = 20 mm 76.9 m MPS Ecoll ±10% 8 m 3 m laserwire detector 16.1 m 35 GeV 25 GeV Cerenkov detector 2 m 12.3 cm 18.0 cm ΔE/E BPM optics Polarimeter chicane M.Woodley
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3.2 Collimation System To remove Halo particles( BG of detector ) SR which hits detector Betatron Collimator Spoiler/Absorber pair at high beta points Energy Collimator Single spoiler at high dispersion point Collimation depth 8-10 x, 60-80 y Muon suppression 5m long magnetized iron filled in tunnel Tail-folding octupole Non-linear focusing of halo particles Core part of the beam unaffected
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3.3 Final Focus RDR Local chromaticity correction Correction of geometric aberration, 2nd order dispersion and higher order aberration
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3.4 IR Design and Integration to Detector FD: compact superconducting magnet inside detector First cryostat is attached to detector Solenoid effect to beam anti-solenoid, DID, anti-DID RDR
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3.5 Extraction Line RDR Transport beam to dump Diagnostics Energy measurement at 1st v-chicane Polarimetry at 2nd IP( R22=-0.5 )
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4. Accelerator Components 4.1 Crab Cavity System To make head-on collision Two 3.9GHz SC 9-cell cavities Crab cavity prototype(RDR)
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4.2 Intra-train Feedback Measurement of beam-beam deflection stripline kicker FONT4: R&D with digital board processor Test is on-going at ATF. Goal latency is 140ns P.Burrows et al 4.3 Polarization Measurement RDR ILC physics requires Polarization measurement with 0.25% accuracy
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4.4 IR Arrangements for two detectors RDR Detector Hall surface assembly Detector self-shield/shielding wall between detectors maintenance when off beam-line
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5. Solenoid Effect Orbit change at IP( in y ) Accuracy in polarization measurement For correction, Detector Integrated Dipole(DID) At higher energy, back-scattered e+e- pair huge BG for detector DID with reversed polarity( anti-DID ) which align orbit to out-going beam line DID/anti-DID A.Seryi, B.Parker
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Anti-Solenoid Overlapping of solenoid field with FD produces huge beam size blow-up. Anti-solenoid can correct the beam size growth excellently. The effect is independent on x-ing angle. With antisolenoids and linear knobs, y = 0.9% Y. Nosochkov, A. Seryi
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6. Beam Tuning Beam tuning method is being studied by computer simulation BBA, Luminosity(beam size) tuning,… Example. BBA+Luminosity tuning with traditional method; Linear knob of SX mover + higher order knob Errors dx/dy for magnets=200um, roll=300urad, field error-1e-4, …….. Disp, Waist,, tilt dK Luminosity G.White
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7. Issues for further Study Hardware Crab cavity system Feedback system SC magnets Monitors( LW,…) ……. Study of beam tuning, beam dynamics, BG,… Alternative design e.g. small x-ing angle/head-on collision including ES separator, large bore magnets for EXT Test facility ESA, ATF/ATF2,…..
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