Home > Program > Session 3 > Hands-on

Hands-on

Change the primary generator class with use of G4ParticleGun.
- See eg. example basic/B2 README page and its B2::PrimaryGenerator class; note that you need to update both .cc and .hh files
Update run.mac and add runs with following primaries: proton, positron, pion-, muon+ Run the macro from your interactive session (Qt).
Add randomizing the particle direction with theta in [0,2*deg], phi [0.,360*deg]. See example basic/B3 README page and its B3::PrimaryGenerator class

Activate interactively storing of the random generator status, run simulation with a retrieved status and check results:

Start application and run command:
```
/random/setSavingFlag true
```
Select a particle type and run 3 events:
```
/gun/particle proton
/run/beamOn 3
```
Copy currentRun.rndm in Run0.rndm (by hand) and save a scene with 3 events.
Run more events with varying the primary particle, eg. run your run.mac.
Restore the random status from the Run0.rndm file:
```
/random/resetEngineFrom Run0.rndm
```
and repeat the commands in step 2) and compare the scene with the saved one.

Visualization: