[Gate-users] Best physics list for positron annihilation.

Tue Nov 17 11:20:39 CET 2015

Hi Andrea,

in your macro you are specifying a source which emits positrons
with a fixed energy! To simulate the range of positrons from
Na-22 decay you better use an ion-source!
Here is the code we use in the EduGATE example “Spectro”
(see also: http://www.opengatecollaboration.org/EduGATE)
& see macro file attached to this eMail.

In the case of Na-22 the aliases in { } are replaced by

Ion_Z_val -> 11
Ion_A_val -> 22

NOTE: this is done automatically in the Spectro example
according to the users’ choice for the Isotope. We simply read
the file: RadioactiveDecay3.3 used in GEANT4.

This finally should give you  more realistic data about the positron
range, since it takes into account the energy distribution of the
emitted positron.

I hope this helps!

Kind regards,

Uwe Pietrzyk

-----------------------------------------
#
# S O U R C E S
#

# source: ion
/gate/source/addSource        IonSource

/gate/source/IonSource/setActivity        {SourceActivity}

/gate/source/IonSource/gps/type Volume
/gate/source/IonSource/gps/shape Sphere
#/gate/source/IonSource/gps/radius 0.1 mm
/gate/source/IonSource/gps/radius {SourceRad}
/gate/source/IonSource/gps/centre 0.0 0.0 0.0 cm

##
## universal ion source
## with arbitrary halflife
##
/gate/source/IonSource/gps/particle ion
/gate/source/IonSource/gps/ion {Ion_Z_val} {Ion_A_val} 0 0
/gate/source/IonSource/setForcedUnstableFlag true
/gate/source/IonSource/setForcedHalfLife 99999999.0 s
/gate/source/IonSource/gps/energytype Mono
/gate/source/IonSource/gps/monoenergy 0. MeV
/gate/source/IonSource/gps/number 1

/gate/source/IonSource/gps/angtype iso
/gate/source/IonSource/gps/mintheta 0. deg
/gate/source/IonSource/gps/maxtheta 180. deg
/gate/source/IonSource/gps/minphi 0. deg
/gate/source/IonSource/gps/maxphi 360. deg

/gate/source/list

#/gate/source/IonSource/gps/confine source_vol

/----------------------------------------------------------------------
Prof. Dr. Uwe Pietrzyk
Diplom-Physiker
Institut für Neurowissenschaften und Medizin / INM-4
Forschungszentrum Jülich GmbH
52425 Jülich
Tel: +49-2461-61 4763
Fax: +49-2461-61 2820
Mobil: +49-162-103-4871
eMail: U.Pietrzyk at fz-juelich.de<mailto:U.Pietrzyk at fz-juelich.de>
http://www.fz-juelich.de/inm/inm-4/DE/Home/home_node.html
&
Bergische Universität Wuppertal
Fakultät für Mathematik und Naturwissenschaften
Büro:  D.08.01
Gaußstr. 20
42097 Wuppertal
Tel: +49-(0)202-439-3523
Fax: +49-(0)202-439-2811
eMail: Uwe.Pietrzyk at uni-wuppertal.de<mailto:Uwe.Pietrzyk at physik.uni-wuppertal.de>
http://www.medizinphysik.uni-wuppertal.de<http://www.medizinphysik.uni-wuppertal.de/>
----------------------------------------------------------------------/

On 17 Nov 2015, at 10:47, Andrea González <andreita_5_92 at hotmail.com<mailto:andreita_5_92 at hotmail.com>> wrote:

Sorry, you are right!
I'm using 22-Na as follows:

/gate/source/addSource na22
/gate/source/na22/setActivity 10000 Bq

/gate/source/na22/gps/particle e+
/gate/source/na22/setForcedUnstableFlag true
/gate/source/na22/setForcedHalfLife 81993600 s
#/gate/source/na22/gps/energytype Mono
#/gate/source/na22/gps/monoenergy 545 keV
/gate/source/na22/gps/monoenergy 195 keV

/gate/source/na22/gps/type Plane
/gate/source/na22/gps/shape Circle
/gate/source/na22/gps/radius 0.5 mm

/gate/source/na22/gps/angtype iso
/gate/source/na22/gps/centre 0. 0. 0. cm

/gate/source/list

Do you thing is correct?

My physics list:

#=====================================
#    Electromagnetic  processes
#=====================================

/gate/physics/addProcess RadioactiveDecay

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

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

/gate/physics/addProcess GammaConversion
/gate/physics/processes/GammaConversion/setModel StandardModel

/gate/physics/addProcess ElectronIonisation
/gate/physics/processes/ElectronIonisation/setModel StandardModel e-
/gate/physics/processes/ElectronIonisation/setModel StandardModel e+
/gate/physics/processes/ElectronIonisation/setStepFunction e+ 0.2 0.1 mm
/gate/physics/processes/ElectronIonisation/setStepFunction e- 0.2 0.1 mm
/gate/physics/processes/ElectronIonisation/setLinearLossLimit electron 0.01

/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 e-
/gate/physics/addProcess eMultipleScattering e+
/gate/physics/addProcess/eMultipleScattering/setModel Urban95Model

/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType e- distanceToBoundary
/gate/physics/processes/eMultipleScattering/setGeometricalStepLimiterType e+ distanceToBoundary

#=========
# Options
#=========

/gate/physics/setEMin 0.1 keV
/gate/physics/setEMax 10 GeV

The problem is about the annihilation range of the positrons in PMMA, because it shows a distrubution much broader than it should be...

I really appreciate your help and comments.

Best regards, Andrea.

________________________________
From: u.pietrzyk at fz-juelich.de<mailto:u.pietrzyk at fz-juelich.de>
To: andreita_5_92 at hotmail.com<mailto:andreita_5_92 at hotmail.com>
CC: gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>
Subject: Re: [Gate-users] Best physics list for positron annihilation.
Date: Mon, 16 Nov 2015 15:40:00 +0000

Dear Andrea,

you didn’t mention the type of problem, but when
you use 22-Na as an ion source you need to specify
the radioactive decay explicitly. In our test and examples,
we use the following:

/gate/physics/addPhysicsList emstandard
/gate/physics/addProcess RadioactiveDecay

and this seems to work fine.
In case you mean something else, please let us know.

Kind regards,

Uwe Pietrzyk

/----------------------------------------------------------------------
Prof. Dr. Uwe Pietrzyk
Diplom-Physiker
Institut für Neurowissenschaften und Medizin / INM-4
Forschungszentrum Jülich GmbH
52425 Jülich
Tel: +49-2461-61 4763
Fax: +49-2461-61 2820
Mobil: +49-162-103-4871
eMail: U.Pietrzyk at fz-juelich.de<mailto:U.Pietrzyk at fz-juelich.de>
http://www.fz-juelich.de/inm/inm-4/DE/Home/home_node.html
&
Bergische Universität Wuppertal
Fakultät für Mathematik und Naturwissenschaften
Büro:  D.08.01
Gaußstr. 20
42097 Wuppertal
Tel: +49-(0)202-439-3523
Fax: +49-(0)202-439-2811
eMail: Uwe.Pietrzyk at uni-wuppertal.de<mailto:Uwe.Pietrzyk at physik.uni-wuppertal.de>
http://www.medizinphysik.uni-wuppertal.de<http://www.medizinphysik.uni-wuppertal.de/>
----------------------------------------------------------------------/

On 16 Nov 2015, at 15:58, Andrea González <andreita_5_92 at hotmail.com<mailto:andreita_5_92 at hotmail.com>> wrote:

Hello, I'm trying to simulate positron annihilitaion for 22-Na in PMMA.

I would like to know wich is the best physics list in this case, because I have problems with my list (standard EM).

Thank you very much.

Andrea.

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