Neutron and photon transport

OpenBNCT’s deterministic solver uses multigroup discrete ordinates, with declared spatial/angular resolution and scattering moments. OpenMC supplies an independent Monte Carlo path. Compare both methods with matched inputs and adequate resolution.

Start with the project workflow

project run orchestrates imaging import, material calibration, beam binding, neutron transport, optional photon transport, boron scaling, metrics and reporting. Current defaults spread histogram bins uniformly per eV and transport capture photons with a separate photon solve.

Inspect [transport] in project.toml: angular order, iteration budget, source weighting, photon policy and the allowed-unconverged setting. A solve that fails to converge requires diagnosis before its dose field is interpreted.

A lower-level neutron example

From the current source checkout:

openbnct sn solve \
  --case benchmarks/synthetic/layered-head-phantom/case.json \
  --data benchmarks/synthetic/layered-head-phantom/multigroup-data-28g-v5-tsl.json \
  --assignment benchmarks/synthetic/layered-head-phantom/assignment.json \
  --source-weighting uniform_in_bin --dose dose.json --output flux.json

This produces a neutron flux and its folded dose. The project workflow additionally uses sn photon-solve and sn merge-photon-dose with compatible photon data. A neutron-only folded photon channel can use local capture-energy deposition, which changes the physical comparison.

Compare the same physics

Match geometry, density/composition, source distributions, thermal scattering and dose-response definitions. project verify uses the project’s boron assumptions and reports whether thermal-scattering physics matches.

Group collapse, mesh/angular resolution, void ray effects and Monte Carlo statistics can each cause differences. Increasing iteration count alone does not resolve those errors. Inspect regional and spatial discrepancies alongside a global mean.

Forward/adjoint and variance-reduction tools support additional research workflows. Their exact data requirements and options are in the usage reference. Read benchmarks for the tested regimes.