Heat Maps

“Heat-map” (really 3D histograms) information of any quantity can be easily extracted from any sim-script. Either by adding lines inside the script itself, or simply by using the --heatmap command-line flag when invoking the script. Assuming your simulation project was created as discussed here and that it was named TriCorder, the sim-script will be named sb_tricorder_sim and you can get help concerning how to extract a heatmap interactively:

$> sb_tricorder_sim --heatmap=help
Produce mesh3d files with extracted quantities from simulated particle
steps, by supplying an argument with the following syntax:

    --heatmap="QUANTITY [where CONDITION] [to FILENAME]"

QUANTITY is an expression based on the G4ExprParser.

CONDITION is an optional filter expression based on the G4ExprParser.

FILENAME is the name of the output file (defaults to "heatmap" if
not provided). Append :(nx,ny,nz) to the FILENAME to modify binning.

Supplying --heatmap with no arguments implies --heatmap=step.edep

Examples:

1) Simply get a map of energy depositions:

    --heatmap=step.edep

2) Same, but only for electrons and gamma and stored in edep_em.mesh3d:

    --heatmap="step.edep where trk.pdgcode==11||trk.is_photon to edep_em"

3) Get approximate energy-flux map by calculating the average
   kinetic energy across the step and scaling with its length:

    --heatmap="0.5*(step.pre.ekin+step.post.ekin)*step.steplength"

Refer to filter expressions for a full list of available parameters in the QUANTITY and CONDITION expressions.

Resulting heatmap files have the extension .mesh3d and can be inspected interactively via the sb_mesh3d_browse command, leading to an interactive display where one can view the 3D data projected onto any cartesian plane, and optionally only using data from selected slices of the third dimension. See the image above for an example.

For reference, here is a complete example of a command (from the dgcode_val bundle) which collects a heat map of electromagnetic energy deposition into a file named edep_em.mesh3d:

$> sb_skeletonsp_sim -n10000 -j8 --heatmap="step.edep where (trk.pdgcode==11||trk.is_photon) to edep_em"