[Gate-users] Is photoneutron yield in Gate/Geant4 underestimated?

von Vangerow Johannes Johannes.vonVangerow at ptw.de
Tue Mar 3 18:02:03 CET 2020

Dear Nicolas,

many thanks for your suggestion. I included the ShieldingLEND physics list in GATE as you suggested. Using the new model, the neutron production rate is closer to what I expect from a simple calculation. Yet, it is still a factor 40-50% less than the calculated value. I’m not shure what is still causing this deviation. I’m using  the photoneutron crosssections from Dietrich  et al. (https://doi.org/10.1016/0092-640X(88)90033-2) for my calculations.

In Geant4, I get reasonable results using the Hadr03 example with a modified version GammaNuclearPhysics.cc including LEND processes as suggested here<https://geant4-forum.web.cern.ch/t/understimating-neutron-flux/999/10>. Do you know if there is a way to use this modified Version of GammaNuclearPhysics.cc in GATE?

Best regards


Von: narbor <nicolas.arbor at iphc.cnrs.fr>
Gesendet: Sonntag, 16. Februar 2020 21:25
An: von Vangerow Johannes <Johannes.vonVangerow at ptw.de>
Betreff: Re: [Gate-users] Is photoneutron yield in Gate/Geant4 underestimated?

Dear Johannes,

From what I know (from Geant4 developers) you can now used ENDF/BVII.1 data for photonuclear reaction (as with MCNP) by selecting ShieldingLEND physics list in GATE.

As you said, previous version of Geant4 (< 10.04) used a parametrized model for photo-nuclear reactions that under-estimate neutrons production for many nuclei (with also a wrong threshold).

Results are clearly better now with the LEND model (ENDF data) for gamma energy lower than 20 MeV.

Best regards,


PS : as John said, the best is always to ask directly Geant4 User Forum for this kind of Geant4 physics questions.


Nicolas ARBOR

Maître de Conférences

Université de Strasbourg - Faculté de Physique et Ingénierie

Groupe de recherche DeSIs - Institut Pluridisciplinaire Hubert Curien

23, rue du Loess BP28 67037 Strasbourg Cedex 2

mail : nicolas.arbor at iphc.cnrs.fr<mailto:nicolas.arbor at iphc.cnrs.fr> / tel :

Le 03/02/2020 à 16:55, John Apostolakis a écrit :
Dear Johannes,

I suggest to post this and similar questions in the Geant4 User Forum (https://geant4-forum.web.cern.ch/ ) , instead of the GATE mailing list, for a response from more Geant4 users and developers.

John Apostolakis,  EP Department, CERN

On 3 Feb 2020, at 16:13, von Vangerow Johannes <Johannes.vonVangerow at ptw.de<mailto:Johannes.vonVangerow at ptw.de>> wrote:


I am just starting to perform simulations in Gate including Neutrons. Concerning that, I performed a simulation with 15MeV photons impinging on a thin (10µm) target. The simulation in Gate / Geant4 yields about a factor 3 less neutrons than a simple calculation using the respective crosssection. So far I tested W and Pb.

In a publication „Quantification of the validity of simulations based on Geant4 and FLUKA for photo-nuclear interactions in the high energy range“<https://www.epj-conferences.org/articles/epjconf/pdf/2017/22/epjconf_icrs2017_06023.pdf> it is stated that Geant4 underestimates the Neutron production. Is this really true? I am using the QGSP_BIC_HP physics list.

Best regards


Dr. Johannes von Vangerow

Software Development

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Email:  Johannes.vonVangerow at ptw.de<mailto:Johannes.vonVangerow at ptw.de>


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