[Gate-users] phase space actor - problem with results interpretation

[Sarah Blind]

Dear Gate user's, 

I have been working on understanding the phase space actor and I have a question maybe someone can help me with: 

I modeled a cell with water in which there is a cluster of nanoparticles. 
I send a 150 keV gamma beam directly on the cluster and throught two phase space actors I'm looking at the different kinds of particles: 
- enterring the cluster and 
- produced inside the cluster. 
(1) As the cell is full of water I'm expecting more compton electrons enterring the cluster than photo-electric electrons. 
(2) Conversely, as my nanoparticles contains bismuth and gadolinium, I'm expecting more photo-electric electrons than compton electrons produced inside the cluster. 
I do observe (2) but I observe (1) only up to 5³ nanoparticles. From 15³ nanoparticles I have more photo-electric electrons enterring the cluster than compton electrons.... I do not understand this results. 
The number of nanoparticles in the cluster should not influence the electrons produced in water before reaching the cluster.... Am I misunderstanding the way the phase space actor works ? 

If someone as an idea, many thanks for the help! 

Sarah Blind 

Here are my scripts: 




world.mac 


/gate/geometry/setMaterialDatabase ../data/GateMaterials.db 

/gate/world/geometry/setXLength 50 um 
/gate/world/geometry/setYLength 50 um 
/gate/world/geometry/setZLength 50 um 
/gate/world/setMaterial Air 

/gate/world/daughters/name cell 
/gate/world/daughters/insert sphere 
/gate/cell/geometry/setRmin 0.0 mm 
/gate/cell/geometry/setRmax 10 um 
/gate/cell/placement/setTranslation 0 0 0 cm 
/gate/cell/setMaterial G4_WATER 
/gate/cell/vis/setVisible 1 
/gate/cell/vis/setColor blue 
/gate/cell/vis/forceSolid false 

/gate/cell/daughters/name nucleus 
/gate/cell/daughters/insert sphere 
/gate/nucleus/geometry/setRmin 0.0 mm 
/gate/nucleus/geometry/setRmax 1 um 
/gate/nucleus/placement/setTranslation 0 0 0 cm 
/gate/nucleus/setMaterial G4_WATER 
/gate/nucleus/vis/setVisible 1 
/gate/nucleus/vis/setColor blue 
/gate/nucleus/vis/forceSolid true 

/gate/cell/daughters/name cluster 
/gate/cell/daughters/insert sphere 
/gate/cluster/geometry/setRmin 0.0 mm 
/gate/cluster/geometry/setRmax 150 nm 
/gate/cluster/placement/setTranslation -5 -6 0 um 
/gate/cluster/setMaterial G4_WATER 
/gate/cluster/vis/setVisible 1 
/gate/cluster/vis/setColor green 
/gate/cluster/vis/forceSolid false 

/gate/cluster/daughters/name NP 
/gate/cluster/daughters/insert sphere 
/gate/NP/geometry/setRmin 0 mm 
/gate/NP/geometry/setRmax 2 nm 
/gate/NP/placement/setTranslation 0 0 0 mm 
/gate/NP/setMaterial AGuIX_65_35 
/gate/NP/vis/setVisible 1 
/gate/NP/vis/setColor red 
/gate/NP/vis/forceSolid true 

/gate/NP/repeaters/insert cubicArray 
/gate/NP/cubicArray/setRepeatNumberX 15 
/gate/NP/cubicArray/setRepeatNumberY 15 
/gate/NP/cubicArray/setRepeatNumberZ 15 
/gate/NP/cubicArray/setRepeatVector 4.5 4.5 4.5 nm 



source.mac 

/gate/source/addSource mybeam gps 
/gate/source/mybeam/gps/particle gamma 
/gate/source/mybeam/gps/ene/type User 
/gate/source/mybeam/gps/hist/type energy 

[historgram] 

/gate/source/mybeam/gps/position -5 20000 0 um 
/gate/source/mybeam/gps/pos/type Volume 
/gate/source/mybeam/gps/pos/shape Cylinder 
/gate/source/mybeam/gps/pos/inner_radius 0 nm 
/gate/source/mybeam/gps/pos/radius 150 nm 
/gate/source/mybeam/gps/pos/halfz 150 nm 
/gate/source/mybeam/gps/ang/type beam2d 

/gate/source/mybeam/gps/ang/rot1 0 0 1 
/gate/source/mybeam/gps/ang/rot2 1 0 0 

physics.mac 

# Geant4-DNA 
/gate/physics/addPhysicsListMixed emstandard_opt3_mixed_emdna 
/gate/physics/SetDNAInRegion nucleus 
/gate/physics/ConstructProcessMixed 

/gate/physics/Electron/SetCutInRegion world 1 mm 
/gate/physics/Gamma/SetCutInRegion world 1 mm 

/gate/physics/Electron/SetCutInRegion cell 10 nm 
/gate/physics/Gamma/SetCutInRegion cell 0.1 mm 

/gate/physics/displayCuts 

/gate/physics/addAtomDeexcitation 

/gate/physics/addProcess PhotoElectric gamma 
/gate/physics/processes/PhotoElectric/setModel LivermoreModel 
/gate/physics/processes/PhotoElectric/setAugerElectron true 
/gate/physics/processes/PhotoElectric/setDeltaRayCut 10 eV 
/gate/physics/processes/PhotoElectric/setXRayCut 10 eV 
/gate/physics/processes/PhotoElectric/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess Compton gamma 
/gate/physics/processes/Compton/setModel LivermoreModel 
/gate/physics/processes/Compton/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess GammaConversion 
/gate/physics/processes/GammaConversion/setModel LivermoreModel 

/gate/physics/addProcess ElectronIonisation 
/gate/physics/processes/ElectronIonisation/setModel LivermoreModel e- 
/gate/physics/processes/ElectronIonisation/setStepFunction e- 0.2 0.1 nm 

/gate/physics/addProcess Bremsstrahlung e- 
/gate/physics/addProcess Bremsstrahlung e+ 
/gate/physics/processes/Bremsstrahlung/setModel LivermoreModel e- 
/gate/physics/processes/Bremsstrahlung/setModel PenelopeModel e+ 

/gate/physics/addProcess eMultipleScattering e- 
/gate/physics/addProcess eMultipleScattering e+ 
/gate/physics/processes/eMultipleScattering/setModel UrbanModel e- 
/gate/physics/processes/eMultipleScattering/setModel UrbanModel e+ 

/gate/physics/SetMinKineticEnergyInRegion world 8 eV 
/gate/physics/SetMinKineticEnergyInRegion cell 8 eV 
/gate/physics/ActivateSpecialCuts gamma 


detecors.mac 

/gate/actor/addActor DoseActor doseDistribution 
/gate/actor/doseDistribution/save output/doseActor.hdr 
/gate/actor/doseDistribution/attachTo cluster 
/gate/actor/doseDistribution/stepHitType random 
/gate/actor/doseDistribution/setPosition 0 0 0 cm 
/gate/actor/doseDistribution/setVoxelSize 1 1 1 nm 
/gate/actor/doseDistribution/enableEdep true 
/gate/actor/doseDistribution/enableUncertaintyEdep true 
/gate/actor/doseDistribution/enableDose true 
/gate/actor/doseDistribution/enableNumberOfHits false 

/gate/actor/addActor PhaseSpaceActor phaseSpace_NP_entry 
/gate/actor/phaseSpace_NP_entry/save output/phaseSpaceNP_entry.root 
/gate/actor/phaseSpace_NP_entry/attachTo cluster 
/gate/actor/phaseSpace_NP_entry/enableProductionProcess true 
/gate/actor/phaseSpace_NP_entry/storeSecondaries false 
/gate/actor/phaseSpace_NP_entry/storeOutgoingParticles false 


/gate/actor/addActor PhaseSpaceActor phaseSpace_NP_IN 
/gate/actor/phaseSpace_NP_IN/save output/phaseSpaceNP_IN.root 
/gate/actor/phaseSpace_NP_IN/attachTo cluster 
/gate/actor/phaseSpace_NP_IN/enableProductionProcess true 
/gate/actor/phaseSpace_NP_IN/enableTrackLength true 
/gate/actor/phaseSpace_NP_IN/storeSecondaries true 








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