Forward Tracking Simulation

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# Forward Tracking Simulation - PowerPoint PPT Presentation

Forward Tracking Simulation. Norman A. Graf ALCPG Cornell July 15, 2003. Overview. Develop track-finding strategies for the forward disk regions in SD. Detectors and support material defined. Ideal MC hits written out. Detector digitization post facto

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### Forward Tracking Simulation

Norman A. Graf

ALCPG Cornell

July 15, 2003

Overview
• Develop track-finding strategies for the forward disk regions in SD.
• Detectors and support material defined.
• Ideal MC hits written out.
• Detector digitization post facto
• Study various readout schemes (pixel, stereo angle)
• Hit merging and ghosting important.
• Include beam backgrounds
• Largest source of hits!
Tracking Strategy
• Find tracks in the 5-layer CCD pixel VXD, extrapolate forward to pick up hits in the disks.
• Conformal mapping of 3D hits simplifies pattern recognition.
• Find tracks from outer radius in, fit, then extrapolate fitted track outwards.
• Use Kalman filter to reconcile track hit prediction with measured strips.
Tracking in VXD
• Pattern recognition for well-measured, separated 3D points is not a problem.
• Five layers provide sufficient redundancy.
• Test pattern recognition in simplified events
•  events: 1, 10, 100, 200, 500 /event
• 3, 5
• 4 <  < 176
• 1GeV < E < 10GeV
Pattern Recognition
• Conformal-mapping technique applied to 3D hits in VXD and forward disks.
• Hits smeared by expected resolutions:
• 5 in r and z for CCD
• 7 in r and r for FWD
• No hit merging!
• No ghosts!
• Treat as combined system:
• Find VXD+FWD tracks in forward region.
1000 Events 500/Event

Missed ~250/500,000 (99.95%)

Track-Finding Time/Event

500 /event

700MHz PIII

Hit-Merging in VXD
• Currently record exact position of MC track’s intersection with sensitive volume in simulations.
• Smear with expected measurement resolution
• Default is 5 microns.
• Hits are currently distinct, even when they are within a pixel (20 microns!).
• Real hits populate ~2×1 set of pixels.
• SLD experience being studied.
• Backgrounds arising from pairs hitting the beampipe have been generated and passed through the full simulation packages.
• One can overlay such events from an arbitrary number of beam crossings onto signal events.
VXD Tracking
• Systematic investigation of pattern recognition in presence of full backgrounds not yet completed, but no problems experienced yet.
• Effects of hit-merging to be studied.
• not expected to be a major factor.
• Efficiencies and resolutions as a function of  and momentum being compiled.
Forward Tracking
• Extrapolate found tracks to hit strips.
• Associate strip hits (either double-sided or back-to-back single-sided) in wedges of z-disks to form 3D space points.
• Need systematic study of occupancies for various designs.
• Can we survive the ghosts? Grow as ~n2!
• Use pixel hits if available.
• Detailed hit merging and ghosting needed!
Forward Disk Detectors
• Many open issues:
• Tiling of disks with wafers:
• Phi segmentation?
• Mix of Si pixel and -strip detectors?
• If pixel, APD or CCD?
• If -strip, double-sided or back-to-back?
• Strip orientations within wedges.
• Shallow- or large-angle stereo?
Next Steps
• Currently developing flexible tools to study effects of disk tiling and strip orientations.
• Will start characterizing various detector layouts in terms of efficiencies and resolutions.
• Continue with impact on physics channels of interest for forward regions.
Summary
• Strategies being implemented to handle pattern recognition in the forward regions.
• Detector digitization infrastructure (hit merging and ghosts) is almost in place.
• Recognize that detector design requires reconstruction input.

Aim for flexible framework to allow iteration.