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Idea Re: How to add thermal neutron scattering to code? 

Forum: Hadronic Processes
Re: Question How to add thermal neutron scattering to code? (Florian Stummer)
Date: 18 Apr, 2018
From: Holger Kluck <Holger Kluck>

I’m a colleague of Florian and I have some new insights into the problem.

The negative-energy errors occurs only for inelastic thermal neutron scattering (G4NeutronHPThermalScattering.cc lines 447-526 for Geant4 10.01, same lines in G4ParticleHPThermalScattering.cc for Geant4 10.04p01) and it is the result of the linear interpolation/extrapolation of the data for sE (line 501). I notice that in our use case the temperature of the used polyethylene is with 50mK much smaller than the lower edge of the interpolation interval which is 264K.

This behavior can be reproduced with the attached macro run1.mac and examples/extended/hardonic/Hadr06 of Geant4 10.04p01 by changing the temperature of ‘water_ts’ from 593K to 50mK on line 92 in DetectorConstruction.cc. With the original temperature of 593K the error does not occur.

My assumption is that the extrapolation breaks down for temperatures far away from the tabulated data. However, I could not find any details about the applicability range of the thermal neutron scattering in the physics reference manual version 10.4.

Can anyone with more knowledge about the thermal neutron scattering comment if my assumption is plausible? Does anyone know the applicability range of the thermal neutron scattering model? Are there any plans to extend them?

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