[Gate-users] Ion source parameters.

[Marcin Balcerzyk]

Dear Gaters.

I wanted to simulate a Na-22 source in my scanner. The scanner works fine
with source Fluor18. To begin with I used ion type source, but got empty
root file for Na-22, with correctly given processed events number. So I
decided to use ion source of F-18 and look what happens – again the root
file subdirectories were empty, but file is about 2MB. The source.mac part
of original working scanner is: 

/gate/source/addSource SourceF
/gate/source/SourceF/setActivity 0.000015 Ci
/gate/source/SourceF/gps/particle e+
/gate/source/SourceF/setForcedUnstableFlag true
/gate/source/SourceF/setForcedHalfLife 6586.2 s
/gate/source/SourceF/gps/energytype Fluor18
/gate/source/SourceF/gps/type Volume
/gate/source/SourceF/gps/shape Cylinder
/gate/source/SourceF/gps/radius 1. mm
/gate/source/SourceF/gps/halfz 1. mm
/gate/source/SourceF/gps/angtype iso
/gate/source/SourceF/gps/centre 0. 0. 0. mm
/gate/source/list

I see that it effectively simulates positron source which is unstable and
has Fluor18 type of energy distribution, and has only distant relation to
ion 9 18 0 0 source. When changing to ion type source I use the macro
(forget that SourceNa really specifies F-18):

/gate/source/addSource SourceNa
/gate/source/SourceNa/setActivity 0.000015 Ci
/gate/source/SourceNa/gps/particle ion
/gate/source/SourceNa/gps/ion 9 18 0 0
/gate/source/SourceNa/setForcedUnstableFlag true
/gate/source/SourceNa/setForcedHalfLife 6586.2 s
/gate/source/SourceNa/gps/monoenergy 0. keV
/gate/source/SourceNa/gps/type Volume
/gate/source/SourceNa/gps/shape Cylinder
/gate/source/SourceNa/gps/radius 1.0 mm
/gate/source/SourceNa/gps/halfz 2.5 mm
/gate/source/SourceNa/gps/angtype iso
/gate/source/SourceNa/gps/centre 0. 0. 0. mm
/gate/source/list

The last command specifies I use Gate 3.0.0. In Users Guide in section 7.2.3
is fluorine  in section 7.2.2  it is written on one hand that you need to
specify for a source: "activity, type of particle(s), energy distribution,
energy value or bounds, angular emission, spatial distribution and location
and half-life". But just then for ion source it is written that: "It
incorporates radioactive decay and atomic de-excitation", hence I understand
all what is produced by a source, including distribution etc. Command ion 9
18 0 0 specifies the 18F with zero charge and ion energy. ASCII outputs for
Hits, coincidences and singles are empty. Omitting ForcedUnstable and
ForcedHalfLife does not help. What is wrong then?

I know that for Na-22 I would have to account somehow for 1.2 MeV gamma
which is there, resulting from 22Ne deexcitation, as I want to include it in
the simulation.

I would appreciate any help from these who work with ion type source.

Marcin Balcerzyk
Instituto Pluridisciplinar
Univesrsidad Complutense de Madrid
Paseo Juan XXIII no. 1
28-040 Madrid
tel. +34 91 3943261
España - Spain