Physics Processes

This page summarizes the process coverage exposed by the current public APIs. For data ingestion and provenance, see Physics Data And Cross Sections.

Capability Levels

NeoMC uses explicit package and capability status rather than broad validation claims:

• complete: implemented for the stated narrow data or helper scope
• approximate: implemented with named approximations or limited physics
• experimental: implemented but still early and not a mature validation claim
• unsupported: rejected or outside current scope

Coupled EM Package

coupled_em owns photon, electron, and positron transport. The package status is approximate because it combines implemented EM processes with explicit fallback and cut policies.

Photon Processes

PhotonInteractionKind supports:

• Rayleigh scattering
• Compton scattering
• photoelectric absorption
• pair production

Public policy controls include:

• ComptonDopplerFallbackPolicy
• PhotonAtomicRelaxationPolicy
• PairTripletRecoilPolicy
• photon rejection-sampling limits
• relaxation stack-depth limits

Electron Processes

ElectronInteractionKind supports:

• elastic scattering
• bremsstrahlung
• excitation
• ionization

Public charged controls include:

• ElectronInelasticAngularPolicy
• ElectronIonizationVacancyPolicy
• ChargedIonizationFinalStateModel
• ChargedBremsstrahlungModel
• ChargedContinuousStoppingModel
• ChargedLossFluctuationModel
• ChargedMscModel

The transport result reports counters for continuous loss, multiple scattering, production cuts, ionization vacancies, relaxation secondaries, and energy accounting.

Positron Processes

The positron surface includes:

• elastic collisions
• bremsstrahlung
• Bhabha collisions
• in-flight annihilation
• at-rest annihilation

Public controls include:

• CoupledPositronPolicy
• PositronAnnihilationFinalStateModel

Decay Processes

Decay data and source generation expose:

• gamma
• beta minus
• electron capture / beta plus
• isomeric transition
• alpha
• neutron
• spontaneous fission
• proton
• electron
• x-ray

DecayEmissionEnergyModel supports:

• line emissions
• allowed beta spectra

Static decay inventory sources can summarize photon, electron, positron, proton, neutron, and alpha emission rates. Actual transport depends on enabled packages.

Proton Package

The proton package is an approximate CSDA electronic-stopping transport path.

Supported controls:

• ProtonNuclearReactionPolicy
• ProtonStoppingModel
• ProtonEnergyStragglingModel
• ProtonMultipleScatteringModel

Current claims are limited to the configured CSDA stopping / range scope. Proton nuclear reactions are unsupported.

Alpha Package

The alpha package is an approximate CSDA electronic-stopping transport path.

Supported controls:

• AlphaNuclearReactionPolicy
• AlphaStoppingModel::nist_astar_water

Current claims are limited to ASTAR-water electronic stopping and range-style energy deposition. Straggling, multiple scattering, charge-state evolution, and alpha nuclear reactions are unsupported.

Neutron Package

The neutron package is experimental.

Supported current behavior:

• MF3 total / elastic / capture microscopic XS interpolation
• data-driven free flight
• capture termination with sink-energy accounting
• approximate elastic final-state policies:
  • forward, no energy loss
  • isotropic, no energy loss

Unsupported current behavior:

• isotope-level material treatment
• inelastic reactions
• fission
• thermal scattering
• temperature treatment
• capture-gamma final states
• delayed neutron or activation-coupled transport

Atomic Relaxation And Secondary Production

Atomic relaxation is controlled through photon and electron material-process policies. Coupled-EM results report photon atomic vacancies, unresolved vacancies, relaxation secondary events, ionization vacancies, and ionization relaxation events.