[gate-users]

[Aurélien Vasseur]

Greetings,

I'm trying to simulate a simple geometry to access only primary interactions. It consists of a block of lead (9cm thick), and I shoot gamma-ray (511keV, 10Bq for 1 sec) in one direction (Source-Surface Distance=10cm). I have no phantom. I set electron cut to 1 km, X- and Delta-Ray cuts to 1 GeV. I activate only photoelectric and Compton effects (low energy for both).
I finally obtain 14 events.

I cannot understand why I have so many Compton effects (20 single diffusions and 7 double) with nCrystalCompton (on the Hits branch) (attached) whereas I have only 10 LowEnCompton on the processName sheet (attached). Could someone explain it to me? The GATE display gives me well 10 Compton.
Moreover, on the Gate display, I can't understand this lines:

*********************************************************************************************************
* G4Track Information:   Particle = gamma,   Track ID = 1,   Parent ID = 0
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
    0        0        0        0     0.511        0        0         0     world_P initStep
    1      100 -1.22e-14 -6.12e-15     0.511        0      100       100    level1_P Transportation
    2      105 -1.29e-14 -6.46e-15     0.349    0.162     5.43       105    level1_P LowEnCompton
    3      108    -1.76     4.19     0.148        0     5.38       111    level1_P LowEnCompton
    :----- List of 2ndaries - #SpawnInStep=  1(Rest= 0,Along= 0,Post= 1), #SpawnTotal=  1 ---------------
    :       108     -1.76      4.19     0.202                 e-
    :----------------------------------------------------------------- EndOf2ndaries Info ---------------
    4      108    -1.36     3.05         0   0.0158     1.39       112    level1_P LowEnPhotoElec
    :----- List of 2ndaries - #SpawnInStep=  1(Rest= 0,Along= 0,Post= 1), #SpawnTotal=  2 ---------------
    :       108     -1.36      3.05     0.132                 e-
    :----------------------------------------------------------------- EndOf2ndaries Info ---------------

*********************************************************************************************************
* G4Track Information:   Particle = e-,   Track ID = 3,   Parent ID = 1
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
    0      108    -1.36     3.05     0.132        0        0         0    level1_P initStep
    1      108    -1.36     3.05         0    0.132   0.0428    0.0428    level1_P eIoni

*********************************************************************************************************
* G4Track Information:   Particle = e-,   Track ID = 2,   Parent ID = 1
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
    0      108    -1.76     4.19     0.202        0        0         0    level1_P initStep
    1      108    -1.76     4.19         0    0.202   0.0826    0.0826    level1_P eIoni
>>> Event 3

Why Gate tracks the electron #2 whereas it comes from a Compton effect? It is the only Compton electron tracked.

Has anyone explanation for it? Please help me.

Aurélien Vasseur

PS: I am working with:
  Mac OSX 10.3.8
  CLHEP1.8.2.0
  GEANT4.6.2.p02
  GATE1.0.2-4.6.2
  Root3.10

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