Detailed Simulation of Crystals short update Weekly dual read out meeting Hans Wenzel Fermilab 23rd February 2010

Outline Goal: make simulation as realistic as possible. Swiss army knife of Crystal simulation. New Version of Geant 4 (4.9.3). New LUT available for BGO reflectivity (based on LBL measurements). (besides glisur and unified) Different geometry. Add and optimize optical (for CPU speed) properties. Allow to set Birks constant. Allow the change of physics list, enable disable optical processes All parameters can be changed via the command line. Code is in CVS (Eshinn) → will move http://cdcvs.fnal.gov/cgi- bin/public-cvs/cvsweb- public.cgi/EShinn/CrystalSim/?cvsroot=ilcdet February 23rd 2010 Hans Wenzel

Crystal Geometry Crystal: 2x2x20 cm Light absorbing Wrapper Also the volume itself Is a sensitive volume. Give result: with/without Birk suppression em/had and other classification Not yet implemented yet: slic like sensitive detector where the optical photons are produced but not tracked Ideal Photodetectors February 23rd 2010 Hans Wenzel

Setting optical properties and Birks Constant in Geant4 (used by scintillation process) G4MaterialPropertiesTable* myMPT1 = new G4MaterialPropertiesTable(); myMPT1->AddProperty("RINDEX", PhotonEnergy, RefractiveIndex1, nEntries); myMPT1->AddProperty("ABSLENGTH", PhotonEnergy, Absorption1, nEntries); myMPT1->AddProperty("SLOWCOMPONENT", PhotonEnergy, ScintilSlow, nEntries); myMPT1->AddConstProperty("SCINTILLATIONYIELD", 8500. / MeV); myMPT1->AddConstProperty("RESOLUTIONSCALE", 1.0); myMPT1->AddConstProperty("SLOWTIMECONSTANT", 300. * ns); myMPT1->AddConstProperty("YIELDRATIO", 1); BGO->SetMaterialPropertiesTable(myMPT1); // Set the Birks Constant for the BGO scintillator BGO->GetIonisation()->SetBirksConstant(0.126 * mm / MeV); February 23rd 2010 Hans Wenzel

BGO optical properties (I) February 23rd 2010 Hans Wenzel

BGO optical properties (II) 2.5 cm BGO February 23rd 2010 Hans Wenzel

Geant 4: produced Scintillation light 2 GeV Muons (2cm BGO): 171500 Scintillation photons/evt. Decay time 300 nsec February 23rd 2010 Hans Wenzel

Geant 4: produced Cerenkov light 2 GeV Muons (2cm BGO): 1430 Cerenkov photons/evt February 23rd 2010 Hans Wenzel

Geant 4: light at the photo detectors 2 GeV Muons (2cm BGO): ----------------------------------- 10500: Szintillation ph/sensor 90: Cerenkov ph/sensor ~ 12% February 23rd 2010 Hans Wenzel

LUT (Reflectivity) Derived from measurements At LBL: M. Janecek, W. Moses IEEE Transactions on Nuclear Science Now part of regulare geant 4 distribution as of 4.9.3 polishedlumirrorair, // mechanically polished surface, with lumirror polishedlumirrorglue, // mechanically polished surface, with lumirror & meltmount polishedair, // mechanically polished surface polishedteflonair, // mechanically polished surface, with teflon polishedtioair, // mechanically polished surface, with tio paint polishedtyvekair, // mechanically polished surface, with tyvek polishedvm2000air, // mechanically polished surface, with esr film polishedvm2000glue, // mechanically polished surface, with esr film & meltmount etchedlumirrorair, // chemically etched surface, with lumirror etchedlumirrorglue, // chemically etched surface, with lumirror & meltmount etchedair, // chemically etched surface etchedteflonair, // chemically etched surface, with teflon etchedtioair, // chemically etched surface, with tio paint etchedtyvekair, // chemically etched surface, with tyvek etchedvm2000air, // chemically etched surface, with esr film etchedvm2000glue, // chemically etched surface, with esr film & meltmount groundlumirrorair, // rough-cut surface, with lumirror groundlumirrorglue, // rough-cut surface, with lumirror & meltmount groundair, // rough-cut surface groundteflonair, // rough-cut surface, with teflon groundtioair, // rough-cut surface, with tio paint groundtyvekair, // rough-cut surface, with tyvek groundvm2000air, // rough-cut surface, with esr film groundvm2000glue // rough-cut surface, with esr film & meltmount February 23rd 2010 Hans Wenzel

How to use the LUT set an environment variable, G4REALSURFACEDATA, to the directory of geant4/data/RealSurface1.0. // ------------- Surfaces -------------- // // Quartz Bar/Air G4OpticalSurface* OpBGOSurface = new G4OpticalSurface("BGOSurface"); OpBGOSurface->SetType(dielectric_LUT); OpBGOSurface->SetModel(LUT); OpBGOSurface->SetFinish(polishedtyvekair); G4LogicalBorderSurface* BGOSurface = new G4LogicalBorderSurface("BGOSurface", BGOBar_phys, expHall_phys, OpBGOSurface); February 23rd 2010 Hans Wenzel

Some results 2 GeV Muons (2cm BGO): 100 Events Name of Surface SzintilatorHits on PD CerenkovHits on PD Dielectric metallic 2430548 23441 etchedteflonair 1814200 16102 groundteflonair 350466 2108 groundvm2000air 335703 2097 groundvm2000glue 965374 7107 polishedtyvek 2484005 24191 etchedtyvekair 2090949 18220 February 23rd 2010 Hans Wenzel