Acts extrapolation

[hupereir]

this changes the default extrapolation mode in ACTS to bidirectional, consistently with genfit and following presentation at https://indico.bnl.gov/event/33420/contributions/126451/attachments/71737/122952/acts_extrapolation.pdf
Also implements forward extrapolation when extrapolating to TPOT.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work for users)
• Requiring change in macros repository (Please provide links to the macros pull request in the last section)
• I am a member of GitHub organization of sPHENIX Collaboration, EIC, or ECCE (contact Chris Pinkenburg to join)

What kind of change does this PR introduce? (Bug fix, feature, ...)

TODOs (if applicable)

Links to other PRs in macros and calibration repositories (if applicable)

Motivation / Context

Align the default ACTS extrapolation behavior with GenFit and the referenced presentation, while ensuring TPOT track states are extrapolated in the forward direction.

Key Changes

• Set the default PHActsTrkFitter extrapolation mode to bidirectional.
• Refactor TPOT track-state propagation to support extrapolation-mode-specific behavior.
• Use forward extrapolation for forward and bidirectional modes.
• Skip TPOT extrapolation in backward-only mode.
• Add surface validity checks and path-length handling for propagated track states.
• Clean up minor whitespace and comments.

Potential Risk Areas

• Reconstruction behavior may change due to the new default extrapolation mode and TPOT propagation logic.
• Additional propagation and trajectory handling could affect performance.
• No IO format or thread-safety changes are expected.

Possible Future Improvements

• Add targeted tests covering all extrapolation modes and TPOT surface edge cases.
• Benchmark propagation performance and validate track-quality changes against reference samples.

AI-generated summaries can contain mistakes; the implementation should be reviewed against the source changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Run ID: a42a6a19-4d92-4aed-bfbd-2cf18145ead2

📥 Commits

Reviewing files that changed from the base of the PR and between 3432859 and f26b79e.

📒 Files selected for processing (2)

• offline/packages/trackreco/PHActsTrkFitter.cc
• offline/packages/trackreco/PHActsTrkFitter.h

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📝 Walkthrough

Walkthrough

Changes

TPOT extrapolation

Layer / File(s)	Summary
Mode-driven TPOT propagation offline/packages/trackreco/PHActsTrkFitter.h, offline/packages/trackreco/PHActsTrkFitter.cc	The default mode is now Bidirectional; TPOT propagation selects source parameters by mode, skips propagation for Backward, computes path lengths through a lambda, and checks TPOT surfaces before propagation. Comments and whitespace were also cleaned up.

Sequence Diagram(s)

sequenceDiagram
  participant PHActsTrkFitter
  participant TPOTSurface
  participant ExtrapolateLambda
  participant ActsPropagator
  PHActsTrkFitter->>TPOTSurface: Retrieve TPOT surface
  PHActsTrkFitter->>ExtrapolateLambda: Select inputs from extrapolation mode
  ExtrapolateLambda->>ActsPropagator: Propagate track parameters
  ActsPropagator-->>PHActsTrkFitter: Return TPOT track state

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Possibly related PRs

• sPHENIX-Collaboration/coresoftware#4188: Modifies the same updateSvtxTrack TPOT propagation path.
• sPHENIX-Collaboration/coresoftware#4305: Refactors the ActsPropagator API used by the new propagation flow.
• sPHENIX-Collaboration/coresoftware#4364: Also changes mode-dependent extrapolation and aligns the default with Bidirectional.

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[sphenix-jenkins-ci]

Build & test report

Report for commit f26b79e9590dc76e14bae21d0e50beab3244c37b:

• builds and tests overall are SUCCESS.
• Build with configuration of alma9.2-gcc-14.2.0 / clang is SUCCESS, 📊clang report (full)/(new), build log
• Build with configuration of alma9.2-gcc-14.2.0 / new is SUCCESS, 📊Compiler report (full)/(new), build log
  • Generating DST and readback: build is SUCCESS
  • Calorimeter QA: build is SUCCESS, 📊 trends
    • 📊 QA-calorimeter for e- at p_T=4GeV : combined Chi2/nDoF = 27.45 / 72, and combined p-Value = 1
    • 📊 QA-calorimeter for pi+ at p_T=30GeV : combined Chi2/nDoF = 41.7331 / 72, and combined p-Value = 0.99837
    • 📊 QA-calorimetric-jet for e- at p_T=4GeV : combined Chi2/nDoF = 0.4559 / 42, and combined p-Value = 1
    • 📊 QA-calorimetric-jet for pi+ at p_T=30GeV : combined Chi2/nDoF = 14.2531 / 42, and combined p-Value = 0.999981
  • Tracking QA with Distortions: build is SUCCESS, 📊 trends
    • 📊 QA-distortions
  • Tracking QA at low occupancy: build is SUCCESS, 📊 trends
    • 📊 QA-Intt : combined Chi2/nDoF = -0 / 72, and combined p-Value = 1
    • 📊 QA-Micromegas : combined Chi2/nDoF = -0 / 20, and combined p-Value = 1
    • 📊 QA-Mvtx : combined Chi2/nDoF = -0 / 54, and combined p-Value = 1
    • 📊 QA-Tpc : combined Chi2/nDoF = -0 / 56, and combined p-Value = 1
    • 📊 QA-tracking : combined Chi2/nDoF = 0.00500184 / 56, and combined p-Value = 1
    • 📊 QA-vertexing : combined Chi2/nDoF = 30 / 112, and combined p-Value = 1
  • Tracking QA for Pythia D0-jet: build is SUCCESS, 📊 trends
    • 📊 QA-Intt : combined Chi2/nDoF = -0 / 72, and combined p-Value = 1
    • 📊 QA-Micromegas : combined Chi2/nDoF = -0 / 20, and combined p-Value = 1
    • 📊 QA-Mvtx : combined Chi2/nDoF = -0 / 54, and combined p-Value = 1
    • 📊 QA-Tpc : combined Chi2/nDoF = -0 / 56, and combined p-Value = 1
    • 📊 QA-tracking : combined Chi2/nDoF = 6.66098e-05 / 50, and combined p-Value = 1
    • 📊 QA-vertexing : combined Chi2/nDoF = 30 / 112, and combined p-Value = 1
  • Tracking QA from run2pp 53877: build is SUCCESS, 📊 trends
    • 📊 QA-intt : combined Chi2/nDoF = -0 / 18, and combined p-Value = 1
    • 📊 QA-micromegas : combined Chi2/nDoF = -0 / 6, and combined p-Value = 1
    • 📊 QA-mvtx : combined Chi2/nDoF = -0 / 18, and combined p-Value = 1
    • 📊 QA-siliconseeds : combined Chi2/nDoF = -0 / 20, and combined p-Value = 1
    • 📊 QA-tpc : combined Chi2/nDoF = -0 / 48, and combined p-Value = 1
    • 📊 QA-tpcseeds : combined Chi2/nDoF = -0 / 28, and combined p-Value = 1
    • 📊 QA-trackfit : combined Chi2/nDoF = -0 / 32, and combined p-Value = 1
  • system alma9.2-gcc-14.2.0, build new: run the default sPHENIX macro: build is SUCCESS, output, trends 📊
  • system alma9.2-gcc-14.2.0, build new: run the default CaloProduction/Fun4All_Year2.C macro: build is SUCCESS, output, trends 📊
  • system alma9.2-gcc-14.2.0, build new: run the default StreamingProduction/Fun4All_Stream_Combiner.C macro: build is SUCCESS, output, trends 📊
  • system alma9.2-gcc-14.2.0, build new: Valgrind test of CaloProduction/Fun4All_Year2.C: build is SUCCESS, 📊valgrind report, trends 📊
  • system alma9.2-gcc-14.2.0, build new: Valgrind test of CaloProduction/Fun4All_Year2_Fitting.C: build is SUCCESS, 📊valgrind report, trends 📊
  • system alma9.2-gcc-14.2.0, build new: Valgrind test of StreamingProduction/Fun4All_Stream_Combiner.C: build is SUCCESS, 📊valgrind report, trends 📊
  • system alma9.2-gcc-14.2.0, build new: run the overlap check for sPHENIX macro: build is SUCCESS, output
  • system alma9.2-gcc-14.2.0, build new: Valgrind test: build is SUCCESS, 📊valgrind report, trends 📊
• Build with configuration of alma9.2-gcc-14.2.0 / scan is SUCCESS, 📊scan-build report (full)/(new), build log
• clang-tidy is SUCCESS, 📊clang-tidy report (full)/(new)
• cpp-check is SUCCESS, 📊cppcheck report (full)/(new)

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