Run a simulation

./VKRun run.mac

Modify the run macro

The run macro file run.mac allows you to modify certain aspects of the simulation. In order to view all the available commands, simply do

./VKRun
PreInit> /control/manual /VK/

Below, we summarize the most relevant commands.

Setup

You can add/remove the following four parts of the setup: (1) The beta detector, (2) the magnet, (3) the catcher foil and (4) the shield. To add all four parts do:

/VK/detector/volumes/betaDetector true
/VK/detector/volumes/magnet true
/VK/detector/volumes/catcherFoil true
/VK/detector/volumes/shield true

To remove any of the parts, simply change the status from true to false.

Note that adding/removing the magnet does not in any way affect the magnetic field.

Magnetic Field

You can enable/disable the magnetic field and scale the magnetic field strength with these two commands:

/VK/field/enable true
/VK/field/maxbfield 0.48 tesla

(the second command sets the maximum field strength to 0.48 Tesla)

Output

Open the output file:

/VK/output/openFile test.root                

If you want to save disk space, you can enable zero suppression. This ensures that events only get saved, if a detector receives a hit:

/VK/output/zeroSuppression true

By default, only the energy deposited in the detectors is saved. However, if you also want to save information about particle trajectories, you can you this command:

/VK/storeTrajectoryData true

Particle source

Set particle type:

/gps/particle e-

Set fixed initial energy:

/gps/energy 1 MeV

Or, use energy distribution corresponding to an allowed beta transition:

/VK/source/betaSpectrum true
/VK/source/betaEndPoint 7.00 MeV

If you wish, you can restrict the energy range with:

/VK/source/betaMinEnergy 5.00 MeV
/VK/source/betaMaxEnergy 6.00 MeV

Set starting point:

/gps/position 0 0 30.5 cm

Set fixed initial direction

/gps/direction 0 0 1

Or, use an isotropic angular distribution

/gps/ang/type iso

You can also restrict the angular range with:

/gps/ang/mintheta  90 deg
/gps/ang/maxtheta 180 deg

If you want to simulate cosmic-ray muons, you can use this angular distribution:

/VK/source/cosmicRayAngDist true

Again, it is possible to restrict the range of angles:

/VK/source/cosmicRayMinZenithAngle  0 deg
/VK/source/cosmicRayMaxZenithAngle 90 deg

Finally, there are commands to specify an extended source distribution:

/VK/source/diskShapedSource true
/VK/source/innerDiameter 0 cm
/VK/source/outerDiameter 60 cm
/VK/source/surfaceNormal 0 1 0

Run the simulation

/run/initialize
/run/beamOn 1000

(the second command sets the number of simulated events to 1000 and starts the simulation)