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Warning Non energy conservation in a hadron elastic scattering between neutrons and protons 

Forum: Hadronic Processes
Date: 24 Apr, 2012
From: Romain Roncin <Romain Roncin>

Dear all,

I am facing non energy conservation in my MC and I need your help to understand what is happening.

Here is the thing : I am creating neutrons in a tank filled with a liquid scintillator. I am using a simple gun : /generator/gun neutron 0 3230 0 0 -1 0 100 0 0 0. I am looking for the protons recoils due to the hadron elastic scattering between neutrons and protons. If everything is working well below ~20MeV I meet strange things above :

- neutron  2112  E: 0 keV;  E0: 100000 keV;  Vertex Position: (0,3230,0)
  TrackID: 1;  ParentID: 0;  Step: 1;  HadronElastic
- proton  2212  E: 100054 keV;  E0: 100125 keV;  Vertex Position: (0,3058.76,0)
  TrackID: 2;  ParentID: 1;  Step: 1;  hIoni
- proton  2212  E: 99797 keV;  E0: 100125 keV;  Vertex Position: (0,3058.76,0)
  TrackID: 2;  ParentID: 1;  Step: 2;  hIoni
- proton  2212  E: 99612.8 keV;  E0: 100125 keV;  Vertex Position: (0,3058.76,0)
  TrackID: 2;  ParentID: 1;  Step: 3;  hIoni

I am using the following HadronElastic Models : - NeutronHPElastic : Emin[GeV]=0; Emax[GeV]=0.02; - G4LElastic : Emin[GeV]=0.02; Emax[GeV]=1.79769e+305;

I don't understand how the neutron can be directly at rest after a scatter with a proton and how this proton can have an energy higher than what was available at the beginning of the process. About 4.4% of all my protons recoils are in the situation showed above.

Is it a known problem ? How can I deal with it ?

Best regards,

Romain Roncin

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1 Idea: Re: Non energy conservation in a hadron elastic scattering between neutrons and protons   (Vladimir Ivanchenko - 08 May, 2012)
(_ Warning: Re: Non energy conservation in a hadron elastic scattering between neutrons and protons   (Romain Roncin - 14 May, 2012)
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