[Gate-users] physics process for photonuclear reaction

[John Apostolakis]

Dear Sookyoung,

I agree with David Sarrut that you need to use a Physics List provided by Geant4 in order to obtain the photo-nuclear interactions which you require.

The process which you describe is a process involving the strong interactions inside the nucleus, since it emits a neutron.  In Geant4 it requires the use of hadronic processes.  All physics lists which I know ( QGSP_BERT, QGS_BIC, FTFP_BERT ) have photo-nuclear interactions included.

There are two versions of gamma-nuclear interaction available in Geant4

a) CHIPS
In Geant4 releases until 9.5 used as default the interaction was modelled using the CHIPS model.  This model was used for many years.  In its original version (ca 2002) it was validated against a lot of photo-nuclear data - there is a publication from this time.  The model continued to evolve, being extended to cope with other types of interactions, so the original validation is no longer reflected in its performance in Geant4 release 9.5.   If you search using Google with search terms similar to "gamma nuclear site:indico.cern.ch" you should find some of the latest validation for it.

I was able to find the following one from 2006
   https://indico.cern.ch/event/4532/session/6/contribution/18/0/material/0/0.ps
Potentially there are other presentation at Geant4 meetings (collaboration meetings and/or hadronic working group meetings) with newer validations.

b) Bertini
In Geant4 release 9.6 and later, the Bertini cascade is used to model it instead.  If you want to use this, you should consider using Geant4 version 10.0 patch 2, which has the latest version of this model -- if it is possible to couple it to Gate 7.0 ( maybe this requires the Git version, or it may not be possible, you will need to find out from the GATE experts.)

Geant4 9.6 included both the CHIPS and the Bertini versions of gamma-nuclear interactions, so it offers the chance to compare.  One caveat is that this was the first release of gamma-nuclear with Bertini, and it required further tuning to obtain reasonable results.

If you need further assistance in choosing a physics list, or have some results which you want to discuss, I suggest to visit the Geant4 User Forum at
   http://hypernews.slac.stanford.edu/HyperNews/geant4/top.pl
and to register. ( You will need to register in order to post questions, and the registration could take a day or two to be processed. )

Please also look at the Physics Lists pages of Geant4, and the other documentation (Physics reference manual, Guide for application developers) for more information about choosing a physics list and the underlying physics models.

Best regards,
John
===================================================
John Apostolakis,  PH Department, CERN
SFT (SoFTware for Experiments) Group
Office: Building 32/ room R-003 (ground floor),  Mail: J27210
Email:  john.apostolakis at cern.ch<mailto:john.apostolakis at cern.ch>       Office Tel:  +41-22-767-7239
------------------------------------------------------------------------------------------

On Aug 28, 2014, at 9:41 AM, David Sarrut <David.Sarrut at creatis.insa-lyon.fr<mailto:David.Sarrut at creatis.insa-lyon.fr>>
 wrote:

Hello,

what Gate version ? If >=7.0, please use the physic list builder<http://wiki.opengatecollaboration.org/index.php/Users_Guide_V7.0:Setting_up_the_physics#New_physics_list_mechanism> and check with G4 documentation what kind of physics you need.

Sincerely,
David


On Wed, Aug 27, 2014 at 1:13 PM, 정숙영 <syjung419 at skku.edu<mailto:syjung419 at skku.edu>> wrote:
Dear GATE users,

As I tried to get results from any Actors that can store the information of particle production, I couldn’t get any of results about neutron.

I want to simulate the photon and neutron generation when the only one kind of high Z material(ex, Pb, Pt, W) bombarded with 20 MeV electron beam.

So far, I found many papers that already calculated neutron flux using other Monte Calro code such as MCNPX, FLUKA but I failed with GATE.

In my opinion, it doesn’t include the physics of photonuclear reaction to separate neutron from the nucleus directly by high energy photon.

I Could you explain what is wrong in my physics setting as below here..?
(I didn’t use hadronic process because that physics is regarding to the incident hadron.)

Thank you in advance.

Best regards,
Sookyoung


====================================================================================
#=============
# For Leptons
#=============

/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
/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
/gate/physics/setDEDXBinning 350
/gate/physics/setLambdaBinning 350



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--
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044
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