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Forum: Hadronic Processes
Re: None (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00
Date: 12 Apr, 2014
From: michel maire <michel maire>

On Wed, 09 Apr 2014 18:22:34 GMT, bbv_nsk wrote:
> Colleagues, I am considering a model with pure Oxygen and 14 MeV neutron
> source. I use the Geant4.10.00. Using tracking verbosity I look at the
> secondary particles emitted after inelastic reactions. Specifically I am
> interested in the reaction (n, n+alpha).
> 
> I see that after each such reaction one gamma particle with the energy
> 4.44 MeV is always emitted. And I have a concern here.
> 
> The emission of gamma particles after such reactions is described in the
> ENDF VII data library with two sets of cross sections. The first set is
> the neutron cross section data and they are given by MF = 3 and MT = 22.
> The second set is the photon production cross sections data that are
> given by MF = 13 and MT = 22. These two sets of data should be used for
> computing the multiplicity of emitted gamma particles by taking a ratio
> of the production cross sections to the neutron cross sections.
> 
> I see that the multiplicity of emitting the gamma quantum with the
> energy 4.44 MeV is less than unity but the Geant4 acts like it is equal
> to unity.
> 
> I looked into the source code and I didn't see that the multiplicity are
> calculated. I think there is a problem in this part of code.
> 
> Could you please comment this issue?
> 
> Thanks,  Bair
> 

 Here is a run of example Hadr03 with attached macro.
 Also  output,  gamma spectrum and  zoom of 4-5 MeV region.
 As you can see, there is 19321 (n, n+alpha) reactions. Number of gamma 4.44 MeV is about 10000

 I do not know if these numbers are compatible with ENDF VII

    Cheers,  Michel

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/12/07.49-69804-neutron.mac.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/12/07.49-1737-output.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/12/07.49-87136-gamma.gif
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/12/07.49-93905-zoom.gif

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1 None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (bbv_nsk - 14 Apr, 2014)
(_ None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (michel maire - 14 Apr, 2014)
(_ None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (bbv_nsk - 14 Apr, 2014)
(_ None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (michel maire - 14 Apr, 2014)
1 None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (bbv_nsk - 14 Apr, 2014)
2 None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (michel maire - 19 Apr, 2014)
1 None: Re: (n, n+alpha) reaction at 16Oxygen, NeutronHP, G4.10.00   (bbv_nsk - 21 Apr, 2014)
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