ZDC Light Guide Monte Carlo

This simulation is based on OpNovice and OpNovice2

Build requirements

• Geant4 compiled with GDML and additional datasets. Be sure to source geant4make.sh

    source /path/to/geant4-install/share/Geant4-[version]/geant4make/geant4make.sh

• CERN ROOT

• CADMesh is required to read CAD models (i.e. stl, step), but is optional for compiling. Avaialble at https://github.com/christopherpoole/CADMesh

main()

define Random Number Engine, initial seed, CAD input and GDML output

G4VUserPhysicsList

• Define particles; including
• *** G4OpticalPhoton ***
• Define processes; including
  • *** G4Cerenkov ***
  • *** G4Scintillation ***
  • *** G4OpAbsorption ***
  • *** G4OpRayleigh ***
  • *** G4OpBoundaryProcess ***

Materials

defines many materials for potential use For our purposes the G4OpticalSurface AlSurface and the G4Material Al and Air will be given optical properties and used for construction.

G4VUserDetectorConstruction

A light guide is made either by simple G4trd or by importing a model via CADMesh. define G4LogicalBorderSurface between the light guide and world volume defines a PMT window sensitive detector at the top of the light guide AlSurface properties can be modified via DetectorMessenger via the following commands

    /lightGuide/surface/Model
    /lightGuide/surface/Type
    /lightGuide/surface/Finish
    /lightGuide/surface/SigmaAlpha
    /lightGuide/surface/Property

CAD models can be imported and positioned via

    /lightGuide/model/CADmodel
    /lightGuide/model/rotate
    /lightGuide/model/translate
    /lightGuide/model/translatePMT

And the optical properties of a sub volume of G4Air which the light guide sits in can be configured via

    /lightGuide/gasProperty

examples of all of these can be found in run1.mac

G4VUserPrimaryGeneratorAction

Use G4GeneralParticleSource to shoot an optical photon into the light guide Particle type and distribution is set in run1.mac

G4UserRunAction

define G4Timer (start/stop) define G4AnalysisManager (output .root file) set verbose levels

PMTHit

stores G4int trackID, G4ThreeVector pos; // Origin position of the photon G4ThreeVector hit; // Location where the photon hit the PMT window G4double energy; // Energy of the photon G4ThreeVector momentum; // Momentum of the photon (direction) G4double time; // Time of arrival of the photon for each hit on the PMT sensitive detector

PMTSD

Records a PMTHit if the photon strikes the PMT window

G4UserEventAction

Show how to count the number of secondary particles in an event

Visualisation

The Visualization Manager is set in the main(). The initialisation of the drawing is done via a set of /vis/ commands in the macro vis.mac. This macro is automatically read from the main in case of interactive running mode.

How to start

• compile and link to generate an executable

  $ mkdir zdclg-build zdclg-install
  $ cd zdclg-build
  $ cmake -DCMAKE_INSTALL_PREFIX=../zdclg-install /path/to/zdclg

This example handles the program arguments in a new way. It can be run with the following optional arguments:

  $ ./lightGuide [-m macro ]
                  [-u UIsession]
                  [-t nThreads]
                  [-r seed]
                  [-o outputFileName]

The -t option is available only in multi-threading mode and it allows the user to override the Geant4 default number of threads. The number of threads can be also set via G4FORCENUMBEROFTHREADS environment variable which has the top priority.

• execute lightGuide in 'batch' mode from macro files

   $ ./lightGuide -m run1.mac

• execute lightGuide in 'interactive mode' with visualization

$ lightGuide
....
Idle> type your commands. For instance:
Idle> /control/execute run1.mac
....
Idle> exit