Running Mokka simulations locally

Extensive sets of simulations are already available and many types of physics can be studied using these sets. However, if a customised detector configuration is needed, it is important to be able to run our own simulations locally, using the PPE batch farm. This wiki explains how to do this, step by step.

Testing Mokka

This is described in the ILCSoft wiki. One can try quickly:

. /afs/phas.gla.ac.uk/data/ilc/software/ilcsoft/v01-14/init_ilcsoft.sh
cd /afs/phas.gla.ac.uk/data/ilc/software/validation/StandardConfig/current
Mokka -M ILD_o1_v05 -e ./particle.tbl bbudsc_3evt.steer

Changing certain detector parameters

Detector parameters are taken from (a default) database. There are many versions of the ILC detectors. One can browse this database via the Mokka Detector Model Database Browser.

To change for example the number of layers in the Hcal, and the sensitive Si layer thickness in Ecal, one would add in the steering file

/Mokka/init/globalModelParameter Hcal_nlayers 36
/Mokka/init/globalModelParameter Ecal_Si_thickness 0.45

to the steering file and use the "-U" command line option to enable the change:

Mokka -M ILD_o1_v05 -U -e ./particle.tbl my_bbudsc_3evt.steer

Visualisation

To visualise the detector geometry set in the steering file for example:

/Mokka/init/BatchMode false

and then in Geant4 prompt type

/vis/open OGL
/vis/scene/create 
/vis/drawVolume
/vis/viewer/set/viewpointThetaPhi 60 45

To draw trajectories:

/vis/scene/add/trajectories 
/vis/scene/add/hits 
/vis/viewer/flush

A good tutorial can be found here.

Running from your own work directory

To be able to customise your scripts and better keep track of the outputs, you should run Mokka from your own directory, e.g.

cd ~
mkdir ILC_Simulations
cd ILC_Simulations
cp /afs/phas.gla.ac.uk/data/ilc/software/validation/StandardConfig/current/bbudsc_3evt* .

Edit now these files, rename and customise them and run (after you've sourced the correct environment as before)

Mokka -M ILD_o1_v05 -U -e ./particle.tbl my_sim.steer

Running Mokka on the PPE batch farm

Here's a simple script (named mokka_test.pbs) that runs the Mokka example on the PPE batch farm:

#PBS -N Mokka_test_1
#PBS -m abe
#PBS -M gary.smythe@glasgow.ac.uk
#PBS -q long5

echo "Running Mokka test 1 ..." 

. /afs/phas.gla.ac.uk/data/ilc/software/ilcsoft/v01-14/init_ilcsoft.sh
cd /afs/phas.gla.ac.uk/user/p/protopop/ILC_Simulations
Mokka -M ILD_o1_v05 -e ./particle.tbl my_sim.steer

echo "Mokka test 1 done!"

To submit the job from any PPE linux account, use the command

qsub mokka_test.pbs

To learn more about PBS commands type man pbs in your terminal.

Using a particle gun

The example above needs around 3 minutes per event. For certain purposes, it is enough to use a simple particle gun instead, and this will run much faster. To do this, replace in the example steering file

/Mokka/init/initialMacroFile bbudsc_3evt.g4macro

with

/Mokka/init/initialMacroFile e-gun.g4macro

where the file e-gun.g4macro contains the following instructions:

/generator/generator particleGun
/gun/particle e-
/gun/energy 100 GeV
/gun/momentumSmearing 5 GeV
/gun/position 0 0 0
/gun/direction 1 0 1
/run/beamOn 3000
exit

Random Direction:

Outlined in the Mokka release_notes_mokka-01-02. Note that this has been replaced in newer versions of Mokka such that the new commands are detailed below.

The new method (which works) is outlined in section 'VI. New Commands for the Particle Gun' in the Mokka release_notes_mokka-05-02. Relevant subsections of IV. are "/gun/thetaSmearing", "/gun/phiSmearing" and "/gun/directionSmearingMode".

Works if replace "/gun/direction 1 0 1" with "/gun/directionSmearingMode gaussian" in the e-gun.g4macro