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

2. 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 bin/public-cvs/cvsweb- public.cgi/EShinn/CrystalSim/?cvsroot=ilcdet
February 23rd 2010
Hans Wenzel

3. 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

4. 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", / 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

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

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

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

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

9. 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

10. 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

11. 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

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