TransportEngine

This class is the primary interface for the Monte Carlo simulation. It allows one to convert a geometric description of materials distributions to an operational Monte-Carlo simulation of photons transport.

Constructor

class TransportEngine(*args, **kwargs)

Generates a new Monte Carlo transport engine. Optional arguments can be used to initialise the attributes described below (following lexicographic order for positional syntax).

>>> engine = goupil.TransportEngine(geometry)

Attributes

TransportEngine.geometry: ExternalGeometry | SimpleGeometry

The geometry seen by Monte Carlo trajectories.

TransportEngine.random: RandomStream

The pseudo-random stream utilised by the Monte Carlo engine.

TransportEngine.registry: MaterialRegistry

The registry stores pre-computed material tables for use in Monte Carlo transport. It is populated from the geometry description when the compile method is called.

TransportEngine.settings: TransportSettings

Settings that control the Monte Carlo simulation. These settings are also accessible directly from the engine for convenience, such as

>>> engine.compton_model
'Scattering Function'

Methods

TransportEngine.compile(mode=None, *, atomic_data=None, **kwargs)

Compiles material tables based on the current engine settings. This function fills the engine’s material registry based on the geometry description. The mode parameter determines the strategy used to construct the material tables. Available options include:

"All"	Compute all possible tables (not recommended for standard usage).
"Backward"	Compute only tables needed for backward transport.
"Both"	Compute tables needed for both forward and backward transport.
"Forward"	Compute only tables needed for forward transport.

If no explicit mode is specified, then the engine will follow either the "Backward" or "Forward" strategy, depending on the configured mode.

The optional argument atomic_data can be used to specify non-default atomic data. Additional build options can be provided as keyword arguments (kwargs). For more details, refer to the compute method in the MaterialRegistry.

TransportEngine.transport(states, /, *, source_energies=None, random_index=None, vertices=None) → numpy.ndarray

Performs a Monte Carlo transport of photon states, which were, e.g., initially generated using the states function. The optional source_energies argument should be used to specify the energies of volume sources, either as a float or a numpy.ndarray of floats, for backward mode. Upon completion, the function returns a numpy.ndarray of integers that map the end-condition of each simulated trajectory. Please refer to TransportStatus for the precise definition of these numbers.

Warning

The states array is modified in-place. This means that the final states overwrite the initial ones. If the initial values need to be conserved, then a copy of the states array must be made before calling this method.

If the random_index parameter is set to True, the transport method will also return an array containing the index of the random stream at the start of each Monte Carlo event. Alternatively, an array of random indices (of the same size as states) can be provided to set the random stream state for each event. This option is typically used to replay previously simulated Monte Carlo events (e.g. with additional vertices data).

Similarly, if vertices is set to True, the transport method will also return an array containing the intermediate vertices of Monte Carlo steps.