Physics Process Coverage

This page is the user-facing coverage map for NeoMC physics processes. It is not a benchmark report and it is not a promise of full validation. It states which process areas are implemented, partial, missing, or out of scope.

Status terms:

• Implemented: production code contains the process and it is usable inside the stated scope.
• Partial: production code contains a simplified, narrow, experimental, or incomplete version.
• Missing: the process is in scope for a general radiation transport core but is not implemented yet.
• Out of scope: the process is not a current product target.

Coverage Matrix

Domain / Particle	Physics process	Status	Scope note
Photon	Geometry free flight and collision sampling	Implemented	Coupled EM photon transport path exists.
Photon	Rayleigh coherent scattering	Implemented	EPDL-style tabulated photon process.
Photon	Compton incoherent scattering	Implemented	Includes policy-controlled Doppler fallback behavior.
Photon	Photoelectric absorption	Implemented	Includes shell and relaxation policy hooks.
Photon	Pair production in nuclear field	Implemented	Produces electron/positron secondaries in coupled EM.
Photon	Triplet production and recoil electron handling	Partial	Recoil policy remains limited.
Photon	Atomic relaxation, fluorescence, Auger emission	Partial	Unresolved relaxation may still require explicit approximation policy.
Photon	Photonuclear reactions	Missing	Important for high-energy shielding and activation.
Electron	Continuous energy loss / restricted stopping	Partial	Coupled charged EM has continuous loss models.
Electron	Moller ionization / delta-ray production	Partial	Secondary and cut handling exists, but precision scope is not closed.
Electron	Bremsstrahlung	Partial	Tabulated model exists; high-energy and angular validation remain incomplete.
Electron	Multiple scattering	Partial	Goudsmit-Saunderson style path exists; step/range scope remains approximate.
Electron	Hard elastic scattering	Partial	Exposed through cutoff policy; not a complete release-grade claim.
Electron	Energy-loss fluctuation / straggling	Partial	Urban/Glandz-style approximation exists.
Electron	Electron-impact ionization relaxation	Partial	Vacancy relaxation still has unsupported/fallback policy paths.
Positron	Continuous energy loss and ionization	Partial	Shares coupled charged EM path.
Positron	Bremsstrahlung	Partial	Same broad limits as electron bremsstrahlung.
Positron	Multiple scattering	Partial	Same broad limits as charged EM MSC.
Positron	In-flight annihilation	Partial	Final-state generation exists, but remains approximate.
Positron	At-rest annihilation	Partial	511 keV photon production and accounting exist, but remain approximate.
Positron	Positronium formation	Missing	Relevant to detailed PET and low-energy positron applications.
Neutron	Free flight with macroscopic cross sections	Partial	Experimental neutron transport path exists.
Neutron	Total, elastic, and capture cross-section interpolation	Partial	Current scope is mainly MF3 total/elastic/capture; nonzero unsupported MF3 channels fail closed.
Neutron	Elastic scattering kinematics	Partial	Includes simplified no-loss and isotropic center-of-mass options.
Neutron	Free-gas thermal energy exchange	Partial	Maxwellian energy-exchange policy exists with explicit accounting; it is not a tabulated thermal scattering law.
Neutron	Thermal scattering S(alpha,beta) law data	Missing	Core gap for moderator-bound thermal neutron transport.
Neutron	Temperature handling for free-gas scattering	Partial	Material temperature affects the free-gas Maxwellian approximation only.
Neutron	Doppler broadening and temperature-dependent evaluated data	Missing	Needed for resonance and realistic thermalized systems.
Neutron	Resonance treatment	Missing	Needed for shielding, activation, and reactor-like problems.
Neutron	Capture sink / local deposit accounting	Partial	Capture can terminate with sink or local kinetic deposit policy.
Neutron	Capture gamma line emission	Partial	Configured single gamma and ENDF MF6/MF12 line-yield tables, including incident-energy yield interpolation, can produce photons for coupled EM.
Neutron	Full capture gamma cascade	Missing	Correlated cascade sampling, continuum spectra, angular data, recoil treatment, and complete energy-release semantics are not complete.
Neutron	Inelastic scattering	Missing	Core gap for intermediate and high-energy neutron transport; nonzero inelastic channels are rejected, not transported.
Neutron	Particle-emission reactions such as (n,2n), (n,p), (n,alpha)	Missing	Required for activation and secondary-particle cascades.
Neutron	Fission	Missing	Prompt/delayed neutrons, fission gamma, and energy release are not implemented; nonzero fission channels are rejected.
Neutron	Delayed neutron and delayed gamma production	Missing	Required for reactor and time-dependent source problems.
Proton	Electronic stopping / CSDA range	Partial	PSTAR water and Bethe-style fallback are available.
Proton	General-material stopping powers	Partial	Current reliable scope is narrow; general material support is incomplete.
Proton	Energy-loss straggling	Partial	Bohr-style option is experimental.
Proton	Multiple scattering and angular/lateral spread	Partial	Highland-style option exists but is not release-grade for general use.
Proton	Nuclear elastic reactions	Missing	Required for proton therapy and shielding accuracy.
Proton	Nuclear inelastic reactions and spallation	Missing	Core gap for accelerator, target, and shielding problems.
Proton	Secondary neutron/gamma/proton/alpha production	Missing	Required for mixed cascades from proton reactions.
Proton	Nuclear stopping	Missing	Important for low-energy charged ions.
Alpha	ASTAR water electronic stopping	Partial	Water CSDA stopping path exists.
Alpha	General-material stopping powers	Missing	Required for realistic material problems.
Alpha	Energy-loss straggling	Missing	Required for detailed alpha dose distributions.
Alpha	Multiple scattering	Missing	Currently not a supported alpha transport claim.
Alpha	Charge-state evolution	Missing	Important for low-energy alpha and ion transport.
Alpha	Alpha-induced nuclear reactions	Missing	Includes (alpha,n) source-term applications.
Light ions	Deuteron, triton, and He-3 particle support	Missing	Particle types are not currently part of the core transport set.
Light ions	Stopping, straggling, and scattering	Missing	Needed before light-ion transport can be claimed.
Light ions	Nuclear reactions	Missing	Needed for D-T, D-D, and related reaction-source problems.
Heavy ions	Ion stopping, charge state, and fragmentation	Missing	Not a near-term core claim.
Heavy ions	Heavy-ion nuclear reactions	Missing	Relevant to heavy-ion therapy and space radiation.
Muon	Ionization, bremsstrahlung, pair production, and nuclear interaction	Out of scope	Not a current target for this radiation transport core.
Pion / kaon / high-energy hadrons	Hadronic cascade	Out of scope	Geant4-scale high-energy hadronic physics is not a current target.
Optical photon	Scintillation, Cherenkov, optical boundary processes	Out of scope	Not part of the current transport core target.
Decay	Decay event source sampling	Partial	Decay data can produce transport source candidates.
Decay	Beta spectrum sampling	Partial	Allowed beta spectrum support exists at source level.
Decay	Full decay chain and daughter buildup	Partial	Deterministic inventory evolution supports daughter buildup for provided decay data, including branching chains.
Decay	Bateman inventory evolution	Implemented	Matrix-exponential inventory evolution supports linear chains, branching ratios, decay counts, time points, and time windows within deterministic inventory scope.
Decay	Isomeric transition cascade correlation	Partial	Some data can be represented; correlated cascade handling is incomplete.
Decay	Electron-capture atomic cascade	Partial	Depends on EM relaxation scope and remains incomplete.
Decay	Spontaneous fission source	Missing	Data type exists, but source/transport support is not complete.
Activation	One-group activation inventory	Partial	Simplified inventory evolution exists.
Activation	Multi-group or continuous-energy activation	Missing	Required for realistic activation workflows.
Activation	Reaction-product inventory coupling	Missing	Neutron/proton reactions are not closed with decay inventory.
Mixed cascade	Source particle routing across packages	Implemented	Mixed source partitioning exists for current particle set.
Mixed cascade	Neutron capture gamma handoff to EM	Partial	Single prompt gamma can be handed to coupled EM.
Mixed cascade	General secondary handoff across all packages	Missing	Reaction secondaries from proton, alpha, neutron, and decay chains are not generally closed.
Energy deposition	Local energy-deposit tally handoff	Implemented	Explicit deposit-site path exists.
Energy deposition	Nuclear recoil dose	Partial	Neutron elastic recoil deposit exists in simplified form.
Energy deposition	Kerma / non-transported secondary accounting	Partial	Needs unified package-wide semantics.

Priority Blocks

1. Neutron completeness: replace the free-gas approximation with tabulated thermal scattering where required, add temperature/resonance treatment, inelastic reactions, fission, and full capture gamma cascade semantics.
2. Proton transport completeness: scattering, straggling, nuclear reactions, and reaction secondary production.
3. Decay and activation inventory: close deterministic inventory evolution with source-term and transport normalization, activation products, and emitted particle source closure.
4. Mixed cascade closure: package-neutral secondary handoff for all transported particle types.
5. Alpha and light-ion support: expand only in response to concrete applications that require those processes.