[Gate-users] Question about coincidence events in root file analysis

ConnorHe hsjbit at 163.com
Fri Aug 27 08:29:30 CEST 2021

Hi, David

      Thanks for your advice, and I tried to remove  "/gate/Phantom0/attachPhantomSD", and checked it.

      In root files, scatter events = 0;      The last left subplot (LORs.png)   did not appear!   

      I thought those events come from the phantom, but I can't explain.....

best regards,

At 2021-08-25 23:41:24, "David Sarrut" <David.Sarrut at creatis.insa-lyon.fr> wrote:


unsure, but please use build-in physic list instead of "/gate/physics/addProcess" stuff (which is deprecated):

also try to remove "/gate/Phantom0/attachPhantomSD" to check if those events come from the phantom (it should be anyway indicated in the root file and remove from the analysis)


On Tue, Aug 24, 2021 at 4:33 AM 升级 <hsjbit at 163.com> wrote:

Dear GATE expert,

              First, I got "True" coincidence event from a root file by filtering:
index = np.where((comptonPhantom1 == 0) & (comptonPhantom2 == 0)
& (eventID1 == eventID2)
& ((RayleighPhantom1 == 0) & (RayleighPhantom2 == 0))

              Then, I see True LORs in attachment(LORs.png),  (as below,  red "*" is source_xyz, green line and dots were LOR and positions)

          The left subplot is my question!  I can’t understand why this is included in True coincidence events

        Could you do me a favor, please?  I'm very confused.  Is it possible that it is a comptonCrystal or RayleighCrystal scattering?

        Any advice would be greatly appreciated. Thanks in advance.

The following is the content of my macro file: (phantom, physics,source)

# Phantom
/gate/world/daughters/name Phantom0 
/gate/world/daughters/insert cylinder
/gate/Phantom0/setMaterial Water
/gate/Phantom0/vis/setColor blue
/gate/Phantom0/geometry/setRmax   1.25 mm
/gate/Phantom0/geometry/setHeight 70. cm
/gate/Phantom0/placement/setTranslation  0. 0. 0. cm 

/gate/physics/addProcess PhotoElectric
/gate/physics/processes/PhotoElectric/setModel StandardModel

/gate/physics/addProcess Compton
/gate/physics/processes/Compton/setModel StandardModel

/gate/physics/addProcess RayleighScattering
/gate/physics/processes/RayleighScattering/setModel PenelopeModel

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

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

/gate/physics/addProcess PositronAnnihilation

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

/gate/physics/processList Enabled
/gate/physics/processList Initialized

/gate/physics/Gamma/SetCutInRegion      crystal 1.0 cm
/gate/physics/Electron/SetCutInRegion   crystal 1.0 cm
/gate/physics/Positron/SetCutInRegion   crystal 1.0 cm

# Source
/gate/source/addSource                  TwoGamma0
/gate/source/TwoGamma0/setActivity      0.15e-3 Ci

/gate/source/TwoGamma0/gps/particle     gamma
/gate/source/TwoGamma0/setType          backtoback
/gate/source/TwoGamma0/gps/energytype   Mono
/gate/source/TwoGamma0/gps/monoenergy   511 keV

/gate/source/TwoGamma0/setForcedUnstableFlag true
/gate/source/TwoGamma0/setForcedHalfLife 6588. s

/gate/source/TwoGamma0/gps/type         Volume
/gate/source/TwoGamma0/gps/shape        Cylinder
/gate/source/TwoGamma0/gps/radius       1 mm
/gate/source/TwoGamma0/gps/halfz        35. cm
/gate/source/TwoGamma0/gps/angtype      iso
/gate/source/TwoGamma0/gps/centre       0. 0. 0. cm
/gate/source/TwoGamma0/attachTo         Phantom0

My best regards,

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Gate-users at lists.opengatecollaboration.org


David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U1294
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
 "2 + 2 = 5,  for extremely large values of 2"
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