[Gate-users] RE: Ion source parameters.

[Marcin Balcerzyk]

Dear Gaters.

It may sound funny to reply to my own posting, but I have solved the problem
of ion source. There is a bug in it; described on posting from Oct 16th 2006
I see the fix of the problem with ion source for Gate 3.0.0: 
 
"yuxuan.zhang at di.mdacc.tmc.edu wrote:
> 
> Hi, Gate users,
> 
> Just a reminder. Last week when I was trying with the ion source, 
> there's no any output
> at all. Later I found out that this is caused by a bug in 
> Geant4.8.0.p01, the
> RadioactiveDecay  function of the ion doesn't work. So if you got this 
> problem and you don't
> want to install another version Geant, maybe you can update the file 
> G4RadioactiveDecay.cc from
> Geant4.8.1 and re-compile it.
> 
> Yuxuan

Hi,
 
Or just include the following lines in GATE sources:
 
In GateDecayPhysics, after line #72, insert the following line:
theIonTable->GetParticle(i)->SetAtomicMass(1);     // GEANT4 Bug Fix #846
 
Sebastien Jan"
 
I was unfortunate to use the combination of software described. 

Now ion source works well, you need to have a working data for:
/geant48/data/PhotonEvaporation2.0 with proper G4LEVELGAMMADATA defined, if
you work for sources decaying to excited states of daughter isotopes, like
Na-22.

Best regards 

Marcin Balcerzyk
Univesrsidad Complutense de Madrid


-----Original Message-----
From: Marcin Balcerzyk [mailto:m.balcerzyk at pluri.ucm.es] 
Sent: Thursday, May 29, 2008 5:21 PM
To: 'gate-users at lists.healthgrid.org'
Subject: Ion source parameters.

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
Univesrsidad Complutense de Madrid