Running simulations

The remage executable drives the simulation from the command line. A short overview of all available options can be obtained with remage --help.

$ remage [OPTIONS] [macros or command string...]

Command line options

Typical invocations supply one or more GDML geometry files and a list of macros to execute:

$ remage -g setup.gdml -- run.mac

Note

The -- is required here to disambiguate since -g can be supplied with multiple arguments.

The most useful options include:

  • macros – macro files or inline command strings. If the given argument is not an existing file it is interpreted as a newline-separated list of commands.

  • -g, --gdml-files – include one or more GDML geometry files (see Experimental geometry).

  • -o, --output-file – sensitive detector hits output file (see Output).

  • -i, --interactive – keep the application open after executing macros and present a Geant4 prompt.

  • -t, --threads – number of worker threads to use.

  • -w, --overwrite – overwrite an existing output file.

  • -q, --quiet/-v, --verbose/-l, --log-level – control the verbosity. Logging levels are debug, detail, summary, warning, error, fatal, and nothing (e.g. -l debug).

  • --version/--version-rich – print version information and exit.

  • -m, --merge-output-files – merge thread-specific output files at the end of execution (see Output).

  • --flat-output – store each Geant4 step as its own row in the output (see Output).

  • --time-window-in-us – time window used when reshaping hits (see Output).

  • -s, --macro-substitutions – provide key=value pairs that will be expanded as Geant4 aliases in macros.

Batch versus interactive mode

By default remage runs all specified macro commands in batch mode and then exits. When -i is given, or the /RMG/Manager/Interactive command is used in a macro, a command prompt is opened after macro execution:

$ remage -i -g setup.gdml -- run.mac
remage>

Executing commands in batch mode

Inline macro commands can also be executed directly from the command line, useful feature when generating macros on the fly (in e.g. a Python script). Multiple commands may be separated by a newline or passed in multiple arguments:

$ remage -i -g setup.gdml -- "/run/initialize \n /run/beamOn 100"
$ remage -i -g setup.gdml -- "/run/initialize" "/run/beamOn 100"

Macro substitutions also work with inline commands. Values are expanded where {name} placeholders appear in the command string:

$ remage -s EVENTS=100 -- "/run/initialize \n /run/beamOn {EVENTS}"

Running from Python

The remage Python package provides the remage.remage_run() function, which accepts the same options as the command line interface. This lets you drive the simulation directly from a Python script:

from remage import remage_run

exit_code, info = remage_run(
    macros="run.mac",
    gdml_files="setup.gdml",
    output="hits.lh5",
    threads=2,
    merge_output_files=True,
)

The returned info object contains metadata from the C++ executable, including logging output and locations of temporary files.