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Silicon Detector Tracking

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Does it matter for P-Flow Calorimetry? Needs study. ... 2. Demonstrate Concept Works (or fix it!) e.g. pattern recognition with backgrounds ... – PowerPoint PPT presentation

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Title: Silicon Detector Tracking


1
Silicon Detector Tracking
  • ALCPG Workshop
    Cornell
    July 15, 2003
    John Jaros

2
SD Tracking Philosophy
  • Si/W calorimetry is expensive, so limit by
    limiting radius and length of tracker
  • Get back BR2 by raising B (5T)
  • Maintain tracking resolution by using Si strips
  • Pillbox tracker shortens z, minimizes material
    for forward tracking, calorimetry, e ID
  • 5 layer VXD ensures good pattern recognition
  • 5 layer barrel measures momentum, confirms
    trajectory for particle flow calorimetry

3
SD Tracking Concept
  • Layout Performance
  • Solid Angle coverage to 100 mr
  • ?p/p2 2 x 10-5
  • 5 Layers of CCD 5 Layers Si ?strip

4
SD Barrel Tracker Concept
  • Si Ladders. Build on GLAST development.
    Daisy-chain detectors to barrel half-lengths.
  • Axial or Small Angle Stereo
  • Readout. Bump bonded ASIC Preamp, shape,
    discrimminate, compress, transmit. Pulsed power.
  • Support. Low mass C-fiber space frame.

5
Some SD Tracking Issues
  • How robust is pattern recognition in the presence
    of backgrounds? SLD experience Tesla
    studies lend credance to VXD pattern
    recognition capability. Full simulation
    studies are underway for VXD and Barrel
    given VXD.
  • Can K0 s and ? s be tracked? Does it matter for
    P-Flow Calorimetry? Needs study.
  • How are exotic, heavy, long-lived particles
    (which decay outside the VXD) tracked? Needs
    study.
  • Do mini-jet (??) backgrounds need good time
    resolution? Under study.

6
Is SD Pattern Recognition Robust?Two
Approaches
  • Plausibiltiy Argument (see below)1. Presume VXD
    pat rec is fully efficient2. Assume VXD tracks
    can be extrapolated to barrel if barrel occupancy
    is low enough.
  • Need a realistic estimate of occupancies
  • Full Geant4 Simulation, including1. All machine
    related backgrounds2. Interactions of
    backgrounds in detectors3. Realistic detector
    response and noiseGenerate and process raw
    dataPattern recognize from measured hits

7
Barrel Occupancy _at_ NLC
  • Backgrounds
    T. Maruyama High pT pairs from
    Hit density from pairs beamstrahlungMeV
    photons frompairs showering nearquad faces
  • Photon Z Distribution (cm)
  • _at_ R25cm
  • Photon Energies (MeV) _at_R25cm

  • 0.1
    1 10

8
EGS SimulationT. Maruyama
  • 300 ?m Si layer in a uniform magnetic field.
  • The layer is divided into 50 ?m wide strips.
  • Energy deposition is calculated in each strip.
  • Ecut 10 keV
  • E? lt.1, .1-.5, .5-1, gt1 MeV ,
  • Converted Electrons can exit Si B 5
    Tesla

9
Tracker Layer 1 Simulation
  • Photon flux 241 photons/4 bunches
  • 5784 photons/NLC train
  • Detector response 113 keV/MinI
    30 keV threshold
  • 25k Channels/Half Barrel

No. of hits 68 strips/train
69 strips/train 106
strips/train
Occupancy 0.27
0.28
0.42
10
Barrel Occupancy/Train
  • Summary for Layer 1 (half barrel r25cm)
    Photon Hits 0.42
    ee- Hits 0.10
    Noise Hits 0.20
    Total Occupancy 0.7
  • Effect on Tracking Estimate probability that
    hits from a track of interest are
    compromised. Require no background hits in 2
    strips track hits or the 2 adjacent strips.
    P(1 - .007)4 97.2
  • SD Pattern Recognition looks OK

11
SD Forward Tracking Ideas
  • Extend barrel tracking philosophy forward 1.
    Pattern Recognize in 5 Layers of CCD 2.
    Extrapolate tracks to forward disks for
    momentum measurement and reliable
    extrapolation to the calorimetry. 3. Global
    Pattern Recognition to follow
  • Design Considerations 1. Extend 5 layer
    tracking over max ? 2. Minimize CCD area/cost
    3. Thin the CCD barrel endplate

12
SD Inner Tracker Concept
  • ? Coverage 5 CCD layers .97 (vs
    .90 TDR VXD) 4 CCD layers .98 (vs
    .93 TDR VXD)
  • Shorten Barrel CCDs to 12.5 cm. Thin endplate.
  • Multiple CCDs on a single 300 ??m Si disk?

13
SD Inner Tracker PerformanceCourtesy B. Schumm
and LCDTRK
  • R-Z Impact Parameter Resolution (?m)
    New SD Old SD
    -log10(1-cos?)
    90 60 41.5 29 20.5 14.5 10.2
    degrees

14
SD Tracking - Design Exercise
  • Goal Bring SD Tracking Design to CDR stage
    Realistic, pre-engineering design study
  • In particular 1. Define SD Tracking
    Concepts 2. Demonstrate Concept Works (or
    fix it!) e.g. pattern recognition with
    backgrounds 3. Develop the Physical
    Picture (ladders, supports, readout and
    power connections, cooling,
    alignment,) 4. Detector and Readout RD
  • Who? U Oregon, UCSC, SLAC
  • Help Needed
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