[Gate-users] Ion source for positron range simulation

[Ashok Tiwari]

Dear Gate Experts, 

I've been facing difficulty to generate the positron range in water using the ion source. For particle and ion source the positron range histogram should be same, but I am getting different histograms! Please advise me if I am missing some information on my macro.

I am simulating positron range in water with O15 & F18 particle source and ion source using GATE. I have not face any problem with particle source of O15 & F18, however I got different positron range  using the ion source. Attached you will find what I have generated. Red circle in the histogram is problematic part! I see some strange feature in my histogram only using the ion source. I also tried to use gamma and electrons filters but that has no effect on output.

Could you please take a look and suggest me what might be the cause of this strange feature? I would greatly appreciate your help. 

Physics list I am using:

/gate/physics/addProcess ElectronIonisation
/gate/physics/processes/ElectronIonisation/setModel StandardModel e+
/gate/physics/processes/ElectronIonisation/setModel StandardModel e-
/gate/physics/processes/ElectronIonisation/setStepFunction e+ 0.2 0.1 mm
/gate/physics/processes/ElectronIonisation/setStepFunction e- 0.2 0.1 mm

# Do I need IonIonisation process? 
#/gate/physics/addProcess IonIonisation
#/gate/physics/processes/IonIonisation/setStepFunction GenericIon 0.1 0.02 mm

/gate/physics/addProcess Bremsstrahlung
/gate/physics/processes/Bremsstrahlung/setModel StandardModel e+
/gate/physics/processes/Bremsstrahlung/setModel StandardModel e-

/gate/physics/addProcess eMultipleScattering
/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType e- distanceToBoundary
/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType e+ distanceToBoundary

/gate/physics/addProcess PositronAnnihilation

/gate/physics/addProcess RadioactiveDecay
/gate/physics/addAtomDeexcitation

I am using following cuts as well, but is has no effect on output.

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

/gate/physics/Gamma/SetCutInRegion      waterbox  0.05 mm
/gate/physics/Electron/SetCutInRegion   waterbox  0.05 mm
/gate/physics/Positron/SetCutInRegion   waterbox  0.05 mm




Thank you.

Regards,

Ashok Tiwari
Graduate Research Assistant
Department of Physics & Astronomy
University of Iowa
Iowa City, 52246, IA
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