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Question scintillator + muons simulation  

Forum: Processes Involving Optical Photons
Date: 09 Apr, 2010
From: Edmundo Garcia <Edmundo Garcia>

Hi, we relatively new using geant4. We want to study the number of photons produced by muons interacting with scintillators (BC 408) of different geometries. Based on example06, we put together the geometry below (not including the surface yet)

We get about 4000 optical photons, which I think is a factor of 100 larger than the ~ 40 expected for a 2 GeV muon going through a 2 cm scintillator. We are using geant493.

We would appreciate any advice.

Thanks, Edmundo.

---------------------------------------------------------- G4VPhysicalVolume* ExN06DetectorConstruction::Construct() {

// ------------- Materials -------------

  G4double a, z, density;
  G4int nelements;

// Air
// 
  G4Element* N = new G4Element("Nitrogen", "N", z=7 , a=14.01*g/mole);
  G4Element* O = new G4Element("Oxygen"  , "O", z=8 , a=16.00*g/mole);

  G4Material* Air = new G4Material("Air", density=1.29*mg/cm3, nelements=2);
  Air->AddElement(N, 70.*perCent);
  Air->AddElement(O, 30.*perCent);

// scintillator
// 
  G4Element* H = new G4Element("Hydrogen", "H", z=1 , a=1.01*g/mole);
  G4Element* C = new G4Element("Carbon", "C", z=6 , a=12.00*g/mole);

  G4Material* scintillator  = new G4Material("scintillator", density= 1.032*g/cm3, nelements=2);
  scintillator->AddElement(H, 30);
  scintillator->AddElement(C, 27);

//
// ------------ Generate & Add Material Properties Table ------------
//
  const G4int nEntries = 3;
  G4double PhotonEnergy[nEntries] ={ 1.4*eV, 5.0*eV,10.*eV };

// // scintillator //

  G4double RefractiveIndex1[nEntries] = {1.58, 1.58, 1.58};
  G4double Absorption1[nEntries] = {210.*cm, 210.*cm, 210.*cm };

  G4MaterialPropertiesTable* myMPT1 = new G4MaterialPropertiesTable();
  myMPT1->AddProperty("RINDEX",       PhotonEnergy, RefractiveIndex1,nEntries);
  myMPT1->AddProperty("ABSLENGTH",    PhotonEnergy, Absorption1,     nEntries);
  myMPT1->AddConstProperty("SCINTILLATIONYIELD",10./MeV);
  myMPT1->AddConstProperty("RESOLUTIONSCALE",1.0);
  myMPT1->AddConstProperty("FASTTIMECONSTANT",0.9*ns);
  myMPT1->AddConstProperty("SLOWTIMECONSTANT",2.1*ns);
  myMPT1->AddConstProperty("YIELDRATIO",0.27);
  scintillator->SetMaterialPropertiesTable(myMPT1);

  // Set the Birks Constant for the scintillator

  scintillator->GetIonisation()->SetBirksConstant(0.126*mm/MeV);

//
// Air
//
  G4double RefractiveIndex2[nEntries] ={ 1.00, 1.00, 1.0};
  G4MaterialPropertiesTable* myMPT2 = new G4MaterialPropertiesTable();
  myMPT2->AddProperty("RINDEX", PhotonEnergy, RefractiveIndex2, nEntries);
  Air->SetMaterialPropertiesTable(myMPT2);

// // ------------- Volumes --------------

// The experimental Hall
//
  G4Box* expHall_box = new G4Box("World",expHall_x,expHall_y,expHall_z);

  G4LogicalVolume* expHall_log
    = new G4LogicalVolume(expHall_box,Air,"World",0,0,0);

  G4VPhysicalVolume* expHall_phys
    = new G4PVPlacement(0,G4ThreeVector(),expHall_log,"World",0,false,0);

// The scintillator
//	
  G4Box* scintillator_box = new G4Box("Scintillator",scintillator_x,scintillator_y,scintillator_z);

  G4LogicalVolume* scintillator_log
    = new G4LogicalVolume(scintillator_box,scintillator,"Scintillator",0,0,0);

   G4VPhysicalVolume* scintillator_phys
    = new G4PVPlacement(0,G4ThreeVector(),scintillator_log,"Scintillator",expHall_log,false,0);

// scintillator surface not yet implemented

//

  //change the color of the scintillator

    G4VisAttributes * yellowTube = new G4VisAttributes(G4Colour(1.,1.,0));
    //yellowTube->SetForceSolid(true);
    yellowTube->SetForceWireframe(true);
    scintillator_log->SetVisAttributes(yellowTube);

    //always return the physical World
    return expHall_phys;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

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