Program installation

These are needed to run the simulation program:

• GEANT4
• ROOT6

It's important that both have been compiled with the same compiler version, otherwise there will be a linking problem when the program tries to create the dictionary for the custom datatype in which some of the data is saved.

To build the program do the following:

cd TestbeamSimulation
cmake -DGeant4_DIR=$GEANT4_DIR source/
make

Environmental variable GEANT4_DIR needs to be set to the Geant4 installation directory. This variable is set in source/CMakeLists.txt.

GEANT4 Version

• We are currently using GEANT4 version 10.7.3 to perform the FoCal Standalone simulation, and we should be consistent with the GEANT4 version we use for the test beam simulations.
• However, our code is now compatible with both versions 10 and 11.
  • To run the simulation using GEANT4 version 10, the line #define G4VERSION_NUMBER 1073 in source/include/constants.hh should be uncommented
  • To run the simulation using GEANT4 version 11, the line #define G4VERSION_NUMBER 1073 in source/include/constants.hh should be commented out

Running & modifying the simulation

Running the simulation is done just by running

./FoCal_Main

in the main directory.

Setting number of events, partcle gun, etc.:

In the main directory you'll find GlobalSetup.mac. There you can change for example the event number or which particle is used.

Changing geometry

There are lots of variables in source/include/constants.hh which change the simulation setup. These might be the most relevant ones:

• UseFoCalE: swith FoCal-E on/off
• UseFoCalH: swith FoCal-H on/off
• UseModifiedSetup
  • if true : use 2021 test beam setup (set NumberPAD=1 and NumberPIX=2, NumberW is the number of W plates in front of pad and pixels)
  • if false: use default setup (set NumberOfLayers so that it is sum of the pad and pixel layers, also set LayerLayout correctly)

Rotate FoCal-H

FoCal-H can be rotated by changing the variable constexpr G4double HCAL_Rot_Y in source/include/constants.hh:

• In the September 2022 test beams at SPS and PS, FoCal-H was rotated 1 degree
• In the November 2022 test beam at SPS, FoCal-H was rotated 2.085 degrees

Visualisation of the setup

Do the following to visualise the setup:

1. Set nameUISession = "qt"
2. Uncomment ui->SessionStart()
3. Uncomment /control/execute visSetup_Simplex.mac in GlobalSetup.mac

Other notes

The code is modified from https://github.com/novitzky/FoCalStandalone, https://github.com/hrytkone/FoCalStandalone and FoCal-H part is from https://github.com/nschmidtALICE/fun4all_eicdetectors/tree/focal_TB/simulation/g4simulation/g4focal.