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TESLA Detector

TESLA Detector. Markus Schumacher, University of Bonn American Linear Collider Workshop, Cornell, July 2003. Requirements Basic Concepts Developments. Requirements from Physics.

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TESLA Detector

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  1. TESLA Detector Markus Schumacher, University of Bonn American Linear Collider Workshop, Cornell, July 2003 • Requirements • Basic Concepts • Developments

  2. Requirements from Physics • momentum: d(1/p) = 7 x 10-5/GeV(1/10xLEP)e+e-gZHgllX goal: dMmm <0.1x GZ  dMHdominated by beamstrahlung • impact parameter: dd=5Å10/p(GeV)mm(1/3xSLD)excellent flavour tagging capabilities for charm and bottom quarks e.g. measurement of Higgs branching ratios • jet energy : dE/E = 0.3/ÖE(GeV)(<1/2xLEP)DMDijet ~ GZ/W  e.g. separation betweene+e-gnnWWgnnqqqq and e+e-gnnZZgnnqqqq LCLEP • reconstruction of multijet final states: e.g. e+e-gH+H-tbtb  bqqb bqqb • hermetic down to q = 5 mradmissing energy topologies (e.g. SUSY and Higgs) Physics determines detector design

  3. Requirements due to the accelerator design • Time Structure: 5 Bunch Trains/s Dtbunch=337ns • Event rates: Luminosity: 3.4x1034 cm-2 s-1 (6000xLEP) • e+e-gqq,WW,tt,HX 0.1 / train e+e-ggggX:~200 /Train • Background from Beamstrahlung: 6x1010 g/BX 140000 e+e-/BX + secondary particles (n,m)  Large B field and shielding But still: 600 hits/BX in Vtx detector 6 tracks/BX in TPC E=12GeV/BX in calorimeters E 20TeV/BX in forward cals. High granularity of detectors and fast readout for stable pattern recognition and event reconstruction

  4. Basic TESLA Detector Concept Large gaseous central tracking device (TPC) High granularity calorimeters High precision microvertex detector All inside magnetic field of 4 Tesla No hardware trigger, dead time free continous readout for complete bunch train (1ms) Zero suppression, hit recognition and digitisation in FE electronics

  5. Overview of tracking system Central region: Pixel vertex detector (VTX) Silicon strip detector (SIT) Time projection chamber (TPC) Forward region:Silicon disks (FTD) Forward tracking chambers (FCH) (e.g. straw tubes, silicon strips) • Requirements: • Efficient track reconstruction /good resolution down to small angles • independent, robust track finding in TPC (200) and in VTX+SIT (7 points) a allows calibration, alignment • excellent momentum resolution d(1/p) < 7 x 10-5 /GeV

  6. Vertex Detector: Conceptual Design Impact parameter: sd ~R1 spoint • 5 LayerSilicon pixel detector • Small R1: 15 mm(1/2 SLD) • Pixel Size:20x20mm2 sPoint =3 mm • Layer Thickness: <0.1%X0 suppression of g conversions – ID of decay electrons minimize multiple scattering 800 billion readout cells Hit density: 0.03 /mm2 /BX at R=15mm a pixel sensors Read out at both ladder ends in layer 1: frequency 50 MHz, 2500 pixel rows acomplete readout in: 50ms ~ 150BX <1% occupancy no problem for track reconstruction expected

  7. readout readout steering Vertex Detector: Technology Options Established Technology: CCDs Excellent experience at SLD (300 billion channels) R&D: efficiency and stability of charge transfer readout speed, thinning of sensors, mechanics, radiation hardness „New“ Technologies: MAPS (Monolithtic Active Pixel Sensors), FAPS DEPFET(Depleted Field Effect Transistor) HAPS (Hybrid Active Pixel Sensors),SiO Each pixel can be adressed individually Only single row active per ladder a smaller power consumption First amplification in pixel a smaller noise R&D: above + building of large devices See Chris‘ talk for more details

  8. M e.g. vertex mass l/sl Expected resolution in r,f and r,z s ~ 4.2 Å4.0/pT(GeV) mm • LEP-c Flavour Tagging • Powerful flavour tagging techniques (from SLD and LEP) • charm-ID: improvement • by factor 3 w.r.t SLD

  9. Inner layer at 1.5cm is very important, e.g. e+e-gZ*gZH ZHgllbb, ZHgllcc, ZHgllgg Flavour Tagging : Recent Studies • W/O inner layer: charm tagging degraded by 10% • Double layer thickness small effect • However: minimal amount of material important • limited number of conversions, electron-id, reconstruction of vertex mass including p0, … Quark Antiquark discrimination via Vertex/Dipole Charge: bottom: p= 80% e= 80% charm: p= 90% e=35%

  10. Gaseous or Silicon Central Tracking Detector? gaseous silicon

  11. Motivation for a TPC • Large no. of 3D space pointsrobust and efficient track reconstruction in high track density environment • Minimal materiallittle influence on calorimetry little multiple scattering small number of conversions • dE/dx  particle identification • Tracking up to large radiiReconstruction of V0, Kink Tracks aid energy/particle flow + sensitivity to new physics ~ new heavy stable particles ~ GMSB SUSY: mgm + G

  12. TPC Conceptual Design Radial space points: 200 Point res.: s < 140 mm (goal:100 mm) Pad size: 6 (r) x 2 (phi) mm2 Large lever arm: RI/A = 40/160 cm Little material: < 3% X0 TPC: d(1/p) = 2.0 x 10-4 GeV-1 +VTX: d(1/p) = 0.7 x 10-4 GeV-1 Gas choice: Ar:CO2:CH4 = 93:2:5 % (CF4 also investigated)Compromise between drift velocity ~ 5cm/ms and neutron cross section Total Drift time 50 ms = 160 BX a 80000 hits in TPC (physics+BG) 8x108 readout cells (1.2MPads+20MHz) a0.1% occupancy No problem for pattern recognition/track reconstruction

  13. Gas Amplification & Point Resolution • Gas Electron Multipliers or MicroMEGAS • better instrinsic point resolution • 2 dimensional readout symmetry • electron signal read out • Small hole separationreduced ExB effects • natural supression of ion feedback • no wire tension a thin endplates Small width of electron cloud (single pad) improve point resolution by charge sharing - chevron pads - large number of small silicon pads - resistive or capacitive coupling of neighbouring pads - larger gap between GEMs and pad plane (details see Ron’s and Dean’s talks)

  14. Intermediate and Forward Tracking SIT:2 Layers of Si-Stripssrf= 10mm • Increase track matching from TPC to VTX by 4 % • Improve Momentum resolution: TPC+VTX: s(1/p) = 0.7 x 10-4 GeV-1 • V0-Reco. Eff. 73 86% (for r=6to11cm) track reconstruction efficieny: e=98.4 (incl. Background hits) +SIT : s(1/p) = 0.5 x 10-4 GeV-1 • Forward tracking (e.g. e+e-WW qqln) • recover mom. resolution at small angles 250 GeV m FTD:7 Disks 3 layers of Si-pixels 50x300mm2 4 layers of Si-strips srf= 90mm FCH:4 Layers Strawtubes or Silicon strips (double sided)

  15. Calorimetry Requirements: • Excellent jet energy resolution much of LC physics depends on reconstruction of invariant masses from jets in hadronic final states • Good energy and angular resolution for photons • Reconstruction of non-pointing photons • Hermeticity ZHHgqqbbbb • Kinematic fits often not applicable – Beamstr., ISR, n, LSP • Intrinsic jet energy resolution is of vital importance  Design optimised for Particle/Energy Flow Algorithm

  16. 60 % charged particles:30 % g:10 %KL,n KL,n p g Particle / Energy Flow The energy in a jet is: Reconstruct 4-vectors of individual particles avoiding double counting Charged particles in tracking chambers Photons in the ECAL Neutral hadrons in the HCAL (and possibly ECAL) • need to separate energy deposits from different particles • small X0 and RMoliere: compact showers • high lateral granularity D ~ O(RMoliere) • large inner radius L and strong magnetic field e • Discrimination between EM and hadronic showers • small X0/lhad • longitudinal segmentation granularity more important than energy resolution

  17. Calorimeter Conceptual Design • ECALandHCAL inside coil • large inner radius L= 170 cm good effective granularity Dx~BL2/(RM Å D) 1/p Dx distancebetween charged and neutral particle at ECAL entrance • ECAL: silicon-tungsten (SiW) calorimeter (preferred choice) • Tungsten : X0 /lhad = 1/25, RMoliere ~ 9mm (gaps between Tungsten increase effective RMoliere) • Lateral segmentation: 1cm2 matched to RMoliere • Longitudinal segmentation: 40 layers (24X0,0.9lhad) • Resolution: sE/E = 0.11/ÖE(GeV) Å0.01 2nd option: 45 layers of Pb(W)+scintillating plates+WLS + 3 layers of Si sensors (.9x.9 cmxcm)

  18. Hadron Calorimeter HCAL ECAL • Longitudinal segmentation: 9-12 samples • 4.5 – 6.2 lhad (limited by coil radius) Two Options: Tile HCAL (Analogue readout) Steel/Scintillator sandwich WLS + Photodetectors (WLS: different geometries) (APDs, SiPM on tiles,…) Lower lateral segmentation 5x5 to 25x25 cm2 Digital HCAL(digital readout) via RPCs,GEMS, small scint. tiles High lateral segmentation 1x1 cm2 resolution: dE/E =0.35/ÖE(GeV) Å0.03 p/m seperation: em =99.8% fakep =10-3

  19. OPAL Calorimeter Reconstruction `Tracking calorimeter’– very different from previous detectors Requires new approach to reconstruction Already a lot of excellent work on powerful particle/energy flow algorithms Still room for new ideas/ approaches jet energy:dE/E = 0.3/ÖE (GeV) dq = 68mrad/ÖE(GeV) Å8mrad without vertex constraintfor photons A lot of R&D activities: Continue evaluation of digital vs analogHCAL Calorimeter segmentation, HCAL active medium Simulation of hadronic showers  test beams

  20. Forward Calorimeters TDR version of mask L* = 3 m Tasks: Shielding against background Hermeticity / veto LAT: Luminosity measurement from Bhabhas (83 to 27 mrad) SiW Sampling Calorimeter aim for DL/L ~ 10-4 require Dq = 1.4 mrad LCAL:Beam diagnostics and fast luminosity (28 to 5 mrad) ~104 e+e— pairs/BX 20 TeV/BX 2MGy/yr Need radiation hard technology: SiW, Diamond/W Calorimeter or Scintillator Crystals

  21. Recent Developments • TDR version of LAT difficult for a precision lumi measurement ? • Shower leakage • Difficulty in control of inner acceptance to~1mm • New L* = 4-5 m version currently being studied. • Flat: better for Lumi. measurement • More Space for electronics etc. • inner radius LAT: 8cm  5cm • Hermetic to 3.9 mrad (was 5.5 with gaps) • less indirect background hits ?? Design in flux + very active R&D

  22. Detector Optimization • Current detector concept essentially unchanged from TDR • Time to think again about optimizing detector design, consider the detector as a whole entity • Optimize design w.r.t. overall detector performance using key physics processes, e.g. • Need unbiased comparison • Same/very similar reconstruction algorithms • Common reconstruction framework • Same Monte Carlo events + OTHER/NEW IDEAS…… • looking at TPC length, extra Si tracker between TPC and ECAL,… • something forgotten ?  devil’s advocate committee

  23. Conclusions Precision physics determines the detector design Basic design almost unchanged compared to TDR Proof of principle for the best suited technologies to be provided by ongoing R&D Optimise Overall Detector Performancein worldwide collaboration to find best detector concept for a future linear collider ! The Physics potential at a LC is excellent, the requirements to the detector are challenging High lumi  large statistics  small systematics need best detector which can be build

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