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ILC Machine-Detector Interface Challenges Philip Bambade LAL-Orsay Workshop on the Future Linear Collider Gandia, Spain, December 1, 2005 Evolution of ee colliders ILC SLC VEPP2 ACO SPEAR CEA BYPASS DCI VEPP2M DAFNE AdA adapted from K. Yokoya and J.-E. Augustin Why shift to linear collider ? storage ring • tunnel, magnets,… • synchrotron radiation losses (RF) E4 / • optimum : equate both costs total cost & size E2 LEP- II Super-LEP Ecm GeV 180 500 HyperLEP 2000 L 27 200 3200 1.5 12 240 2 15 240 km E GeV $tot 109 SF unacceptable scaling ! Linear collider concept idea : cost and size E pre-accelerator few GeV source KeV damping ring few GeV few GeV bunch compressor 250-500 GeV main linac extraction & dump final focus IP collimation from N. Walker RF technology ( gradient, efficient power transfer) focus beam phase-space control and stability synchrotron radiation still drives design… LC machine : basic concepts example : TESLA DETECTORS FINAL FOCUS POSITRON SOURCE LINAC DAMPING RING POLARISED ELECTRONS nbNe2 f L~ HD 4xy D = disruption (pinch) linac rep. rate f ≪ ring frequency focus beam to small IP size very strong (achromatic) lenses ultimate limit (K. Oide) : energy from synchrotron radiation in lenses copious synchrotron radiation from colliding bunch space-charge Beam-beam mutual focusing simulate collision with initial y offset main tool at SLC (and LEP) SLAC-PUB-6790 detectable post-IP deflection Main ILC specifications from ILCSC (September 2003) Ec.m.s = 0.2 - 0.5 TeV, upgradeable to ~ 1 TeV, capable of efficiently changing the energy ( scanning) L > 500 fb-1 in 4 years after initial year of commissioning Stability and precision of beam energy < 0.001 Electron polarization > 80 % 2 interaction regions for 2 detectors, with similar Ec.m.s and L capabilities, among which one should have a crossing-angle to allow a future upgrade to collisions Optional upgrades: , ee, e, GigaZ, polarized e Successful SLC (warm / 3 GHz) experience 10 10 9 9 8 8 X * y 7 6 6 5 5 2 7 x* y (microns ) Beam Size (microns) IP Beam Size vs Time 4 SLC Design (x * y) 4 X 3 3 Y 2 2 1 1 0 0 1985 1990 1991 1992 1993 1994 1996 1998 Year dipole IP Dx sextupoles 0 m 0 1/ m R 0 0 0 0 at optical focus : “depth of focus” • want small y • need z y SET z y 0 0 0 0 m 0 0 1/ m FD L* z y* hour-glass effect ILC beam parameter optimization(s) L/Lnom~ 2.8 nbNe2 f L~ HD 4xy nominally 2 N e Ecm BS ~ z(xy)2 SET z ~ y 2 n L~ Pelectrical BS z HD L~ Pelectrical BS HD ECM n, y y ECM n, y Design machine and detector ILC beam parameter for this set: L~ Pelectrical BS HD ECM n, y optimization L/Lnom ~ 2.8 Nominal Luminosity [cm-2 s-1] ~ 2 1034 BS backgrounds PRECISION PHYSICS •ECM resolution •Forward hermeticity •Beam-beam systematics physics detector machine damping ring compression injection LC is open system “the experiment starts at the gun” LC performance “beam-beam interaction dominated” detector LC design & operation : new challenges ! HEP community strongly involved Special needs for some physics topics : Luminosity + energy + polarization – correlations – forward region – background crossing-angle choice Examples of direct impact on precision physics program (more work on quantitative assessments needed) Include detector & physics performance in global ILC parameter optimization 1. Cécile Rimbault Strongly biases luminosity measurements if not well corrected precision goal = 10-3-10-4 Cécile Rimbault 2. Cécile Rimbault Cécile Rimbault Comparison with LDC occupancy tolerance Tolerance : 3 hits/cm2/bx (TDR) Using : Nb hits/particle = 3 rough estimate Surface L1 = 1.5cm* 10cm*2 = 94 cm2 LDC tesla nominal lowQ largeY lowP highLum NincVD/bx 94 86 39 90 220 240 Nhits/cm2/ bx 3.0 2.7 1.2 2.9 7.0 7.7 high Lum & lowP are beyond the occupancy tolerance (C. Rimbault) (Geant4-based) Precision of secondary vertex charge determination as function of beam pipe radius •pipe ddd •Dddd •d Luminosity factor (S. Hillert & C. Damerell) study also NEEDED to probe occupancy tolerance 3. error mtop, msleptons 2 10-4 mW 5 10-5 reconstruction top quark threshold S.Boogert Beamstrahlung spread dependence with IP beam offset Nominal Low Power M. Alabau Expect variations larger by factors 2-4 with “Low Power” for similar IP offset feedback criteria 4. very forward region crossing-angle choice head-on or 2mrad IP geometry forward region calorimetry at low angle 1. luminosity 2. veto 20 or 14 mrad Present ILC base-line Crossing-angle pros and cons spent beam extraction (& diagnostics) (highest energy & luminosity BS local solenoid compensation crab-crossing Special IR magnet designs Masking, collimation & backgrounds Beam diagnostics from pairs Very forward hermeticity 20 (14) mrad 2 (0) mrad easier harder ) needed not needed essential not essential yes slightly harder ? ….under study…. ? slightly worse a bit better slightly worse a bit better V. Drugakov Electron veto efficiencies in BeamCal need to be introduced into stau analysis V. Drugakov Ring 1 Ring 3 Ring 1 Ring 3 QUESTION TO EXPERIMENTAL COMMUNITY: Trade-off between: 1. Luminosity (factor 2-3, up/down) 2. Stronger beam-beam effects: luminosity spectrum, forward hermeticity, backgrounds, systematics,… Indirect consequences through impact on configuration choices and physics options 2 IR complementarity, balanced risks and flexibility with 1 large & 1 small crossing-angle 1 IR (+ 2nd later) crossing-angle choice affects articulation of physics program Only 1 IR priority to ILC operability at highest energies & luminosities probably implies large crossing-angle choice Options if ILC must start with single IR: N.B. These arguments are subject to debate in the ILC-WG4 1. 2. -Best choice to eventually achieve highest energy and luminosity beyond nominal goals -2nd IR optional (later?), dedicated to precision studies in specific channels, if physics requires it - Best conditions for physics at nominal energies and luminosity - 2nd IR optional (later?), to enable the option and highest energy and luminosity beyond nominal goals, if physics requires and after accumulating learning experience Increasing awareness to MDI challenges in HEP ILC community Participation of Spanish groups in this work (along side detector and physics activities) important and very welcome: