Fix double normalization in random ray VTK flux

[agourakis82]

Summary

Fixes #4137. Random-ray VTK flux was normalized by the active batch count twice.

RandomRaySimulation::simulate() already applies the final source normalization to the scalar flux. The flat and linear source-domain point evaluators then divided their values by the active batch count again. Linear source moments also did not receive the final normalization applied to scalar flux.

This patch:

• applies the final normalization factor to linear flux moments;
• removes the duplicate active-batch division from flat-source point evaluation;
• removes the duplicate active-batch division from linear-source point evaluation;
• adds a regression test comparing mean random-ray VTK flux with the source tally.

Validation

• ctest: 14 passed, 1 skipped
• focused random-ray regression tests: 12 passed
• ruff check tests/regression_tests/random_ray_vtk_normalization/test.py
• git diff --check

The focused regression test fails against the unpatched baseline and passes with this change. OpenMP cluster validation was attempted, but the workspace Slurm executor terminated even a minimal probe with RaisedSignal:53 before running the payload.

Summary by CodeRabbit

• Bug Fixes
  • Corrected flux normalization for random-ray simulations using linear sources, including flux moments.
  • Improved consistency between flux values shown in VTK plots and source-tally results.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 8b7c08c6-599e-4df9-ad3e-4d29a4062f77

📥 Commits

Reviewing files that changed from the base of the PR and between aa4afc4 and 104ec66.

📒 Files selected for processing (5)

• src/random_ray/flat_source_domain.cpp
• src/random_ray/linear_source_domain.cpp
• src/random_ray/random_ray_simulation.cpp
• tests/regression_tests/random_ray_vtk_normalization/__init__.py
• tests/regression_tests/random_ray_vtk_normalization/test.py

💤 Files with no reviewable changes (1)

• src/random_ray/linear_source_domain.cpp

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📝 Walkthrough

Random-ray point evaluation no longer divides accumulated flux values by the active-batch count. Simulation also normalizes linear-source flux moments with the scalar-flux normalization factor. A regression test compares VTK flux values with a source tally.

Changes: Random-ray VTK flux normalization

Layer / File(s)	Summary
Normalize point-evaluation flux and validate VTK output src/random_ray/random_ray_simulation.cpp, src/random_ray/flat_source_domain.cpp, src/random_ray/linear_source_domain.cpp, tests/regression_tests/random_ray_vtk_normalization/test.py	Simulation applies the scalar-flux normalization factor to linear-source flux moments. Flat- and linear-source point evaluation use accumulated values without another active-batch division. The regression test compares mean VTK flux with the source-tally mean.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 104ec

The test can exercise the linear flux contribution, and no actionable issue remains from this review. The change is ready for normal merge checks.

Pre-merge checks · 4 · 1

Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks (4 passed)

Check name	Status	Explanation
Title check		The title clearly and concisely describes the primary fix: preventing double normalization of random-ray VTK flux.
Description check		The description explains the bug, motivation, implementation, linked issue, regression test, and validation results. It omits the template's AI Assistance and Checklist sections, but the core descript…
Linked Issues check		The changes satisfy the coding requirements in issue #4137. RandomRaySimulation::simulate() now applies the final source normalization factor to flux_moments_t for linear sources. Both point evalu…
Out of Scope Changes check		The pull request changes only random-ray normalization code and its regression test. These changes directly support issue #4137 and do not demonstrate unrelated behavior or files.

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