[Gate-users] No annihilations in the phantom but just in the source

Uwe Pietrzyk u.pietrzyk at fz-juelich.de
Wed Jun 30 17:38:58 CEST 2010


coming back to your initial mailing.  Your also need to add the process marked
with <<<<<<<<<<<<<<
This will give you a lot of scattering and interaction. In vacuum, the positron
goes far enough to reach the detector.

/gate/physics/addProcess LowEnergyPhotoElectric gamma
/gate/physics/addProcess LowEnergyCompton gamma

/gate/physics/addProcess MultipleScattering

/gate/physics/addProcess ElectronIonisation e-
/gate/physics/addProcess ElectronIonisation e+        <<<<<<<<<<<<<<<<<

/gate/physics/addProcess PositronAnnihilation

Also, since I looked at your macros, you have to set the size of world large
enough to cover the whole system.

Hope, this is still useful, since you seem to have found the problem.

Kind regards,

U. Pietrzyk
On 30.06.2010, at 10:59, Dimitri DWORAK wrote:


I have simulated a spherical source  of F18 with a radius of 0.5mm in a Phantom of Plexiglas but when i plot all
positions of annihilation between positrons and electrons giving by the Singles file i see that all annihilations are
in the source (graph is attach to the mail ) they are no scattering of positrons in the phantom.

I have check my physic list and the Multiplescattering  option for e+ and e- is in it.

Could you help me please?

DWORAK Dimitri

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Prof. Dr. Uwe Pietrzyk
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