Status of PbGl MC

Emanuele LeonardiINFN Roma

P326 Veto Meeting – 11/9/2007

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Geometry

• PbGl bloc design from Opal docs– ~10x10cm front face– ~11x11cm back (readout) face– Blocs with 16 different shapes– Cylindrical light-guide on back face (6-8 cm)– Currently we use squared faces with a

0.5cmx0.5cm center displacement• Can be changed via datacard• Real shape will be added if needed

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Materials

• Leadglass + light guide : Schott SF57 • Density :

– Datasheet: 5.51 gr/cm3 – Other sources: 5.57-5.6 gr/cm3– Used: 5.57 gr/cm3

• Composition:– SIO2 PbO Na2O K2O As2O3– 22-26% 72-76 0.5-1.5 0.5-1.5 Traces Datasheet– 24% 74% 1% 1% 0% Used

• Radiation length:– 1.5 cm from literature– 1.507 cm from G4

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Physics List

• August version of PbGl MC used an optical-studies-oriented PL– E.m. + optical processes only– No photonuclear effect!

• BTF MC uses the standard LHEP PL– E.m. and hadronic processes– Photonuclear effect included

• Total cross section OK, neutrons production not optimal

– No optical processes

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Physics List

• New PL created last week by merging LHEP with optical physics

• Comparison with LHEP is OK– Measured cross section with 10^6 event

• All optical processes are there– Tests are underway

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// default cut value is 0.7mm as in LHEP 4.2defaultCutValue = 0.7*mm;// EM PhysicsRegisterPhysics( new G4EmStandardPhysics("standard EM",ver));// Synchroton Radiation & GN PhysicsRegisterPhysics( new G4EmExtraPhysics("extra EM"));// General Physics - i.e. decayRegisterPhysics( new G4DecayPhysics("decay",ver) );// Hadron Elastic scatteringRegisterPhysics( new G4HadronElasticPhysics("LElastic",ver,false));// Hadron PhysicsRegisterPhysics( new HadronPhysicsLHEP("hadron"));// Ion PhysicsRegisterPhysics( new G4IonPhysics("ion"));// Optical PhysicsRegisterPhysics( new OpticalPhysics("optical"));

pManager = G4OpticalPhoton::OpticalPhoton()->GetProcessManager();pManager->AddDiscreteProcess(theAbsorptionProcess);pManager->AddDiscreteProcess(theRayleighScattering);pManager->AddDiscreteProcess(theBoundaryProcess);pManager->AddDiscreteProcess(theWLSProcess);

theParticleIterator->reset();while( (*theParticleIterator)() ){ G4ParticleDefinition* particle = theParticleIterator->value(); pManager = particle->GetProcessManager(); if(theCerenkovProcess->IsApplicable(*particle)){ pManager->AddContinuousProcess(theCerenkovProcess); } if(theScintProcess->IsApplicable(*particle)){ pManager->AddProcess(theScintProcess); }}

LHEP

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Optical Properties• Refractive index : 1.84 @1.9eV - 1.91 @3.1eV• Absorption length:

– Datasheet: 420cm @1.9-2.3eV, 0cm above 3.1eV– Measured: 60cm @1.9-2.3eV

Energy Ref.Idx A.L. A.L.(measured)1.88914eV 1.83650 420cm 60cm1.92582eV 1.83808 420cm 60cm1.95929eV 1.83957 420cm 60cm2.10392eV 1.84636 420cm 60cm2.11001eV 1.84666 420cm 60cm2.27035eV 1.85504 420cm 57cm2.55059eV 1.87204 144cm 49cm2.58300eV 1.87425 130cm 48cm2.84497eV 1.89393 34cm 29cm3.06360eV 1.91366 8cm 8cm

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Optical Surface

• A real PbGl bloc is wrapped with a black sheet of vinyl fluoride+polyester. Inside of sheet is coated with Al to improve reflectivity.

• Current simulation applies Al coating directly to PbGl surface

• Surface model simulates spike reflection with a fixed reflectivity– default is 90%, easy to modify

// LeadGlass-Aluminum coatingG4OpticalSurface* OpPbGlSurface = new G4OpticalSurface("PbGl_Al");OpPbGlSurface->SetType(dielectric_metal);OpPbGlSurface->SetFinish(polished);OpPbGlSurface->SetModel(glisur);

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Hits

• Optical photons are tracked till:– they are absorbed by PbGl– they are absorbed by Al wall– they reach the PMT surface and are not reflected

• A Hit is a photon reaching the PMT surface• Hits data are written to file in a pure ROOT

format (no G4 dependencies)

Int_t fPMTId; // Id of PMTDouble_t fETot; // Energy of photon (eV)Double_t fTime; // Hit time (ns)Double_t fRadius; // Impact distance from PMT center (mm)Double_t fCosTheta; // Cosine of impact angle on PMT surface

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Histograms

• Several histograms are filled by the simulation program– When an optical photon is generated– When an optical photon is absorbed– When a hit is created– At the end of each event

• Histograms can be easily added

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Digitization

• Digitization program is G4-independent

• Reads Hits file in ROOT format

• Writes Digi file in ROOT format

• Simple model for the Hamamatsu R2238 PMT is used– Q.E.(λ)– Calibration from BTF