Tracking Simulation in North America

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Tracking Simulationin North America

• Norman A. Graf
• ALCPG Meeting, SLAC
• January 8, 2004

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Overview

• Improving Detector Response Simulation
• Intrinsic (Geant4, dedicated simulations)
• Digitization (pixel size, strip pitch,
  orientation)
• Raw data? hits
• Including Detector Backgrounds
• Noise, machine and physics
• Pattern Recognition
• Track Fitting

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Tracker Hits

• Defer digitization to post-Geant4 to speed up
  simulations and investigate effects of readout.
• e.g. Si ?strip pitch, TPC pad size, CCD pixel
  size.
• Have defined generic tracker hit information
  for full simulation output.
• SimTrackerHit in common LCIO format.
• In studies to-date, hits have simply been smeared
  by expected resolutions.
• No hit-merging or ghosting.

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VXD CCD Digitization

• Near-term focus on improving digitization.
• Defined interface for pixelizing hits.
• First implementation incorporates pixel
  distributions from SLD into simulations as
  functions of track parameters (Nick Sinev UO.)
• Implementing pixel clustering and hit position
  and uncertainty determination.
• Being incorporated into mainstream code.

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Si ?-strip Digitization

• Defined interface for hits?strips w/ADC.
• First implementation uses software based on BaBar
  code (C. Flacco, UCSC). Includes diffusion,
  charge expansion, noise.
• Implementing strip clustering and hit position
  and uncertainty determination.
• Being incorporated into mainstream code.

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TPC Digitization

• Dan Peterson presented a nice talk on work he has
  been doing to digitize the TPC hits.
• Will collaborate with him (and others, e.g. M.
  Ronan, D. Karlen) to get this feature into the
  mainstream code.
• Personally not sure how to correctly include time
  offsets for overlaid events

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Backgrounds

• Much recent work has been done to systematically
  generate backgrounds from ee- ??- pairs and
  ???hadrons (T. Barklow, T. Maruyama).
• Mask BDS elements have been included in GEANT4
  using LCD XML detector description plus dedicated
  drivers for the masks, luminosity monitors and
  beam delivery system (T. Behnke).
• G4 event source reads in GuineaPig output (TB).
• Started generating data samples.
• Machinery to overlay events exists.

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SiD Barrel

• Extend VXD-found tracks into SiD Barrel, picking
  up additional axial hits (S. Wagner).
• Axial-only track finding in Barrel (SW).
• Find MIP-clusters in EM Calorimeter (M. Charles).
• Study alternate geometries?
• Number placement of barrels.
• Strip pitch, z segmentation, stereo layers.

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SiD Forward

• Study effects of disk tiling and strip
  orientations.
• Understand impact of ghosts when creating 3D hits
  vs. adding strip hits to VXD tracks.
• Characterize robustness in presence of
  backgrounds (physics and machine).
• Investigate alternate geometries.
• Inner pixels, outer strips?

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Alternate Detector Designs

• Revisit the VXD design with an eye towards
  improving its pattern-recognition capabilities.
• longer inner layer at larger radius?
• better forward performance
• larger outer radius?
• better b and V performance
• additional layer(s), forward disk elements?
• redundancy
• protection against possible layer 0 degradation
• better b and V performance

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Summary

• Near term emphasis on improved detector
  digitization.
• Active work on CCD, TPC, Si ?-strips
• Full background sets available, being pushed
  through the full simulation.
• Aiming for results at LCWS incorporating
  realistic hit reconstruction from raw data and
  in the presence of full backgrounds.