Problem of thermal neutron simulation

In these picture, you can find a same phenomenon ,i.e. neutron’s kinetic energy sometimes increase with elastic-scattering with materials. It’s not scientific. What’s more ,recoiling particle’s energy is not right too. So, I think the calculate method is wrong. My physic list is QGSP_BERT_HP.

Just to help in checking this, which version of Geant4 is this, and which OS/compiler version is being used? Thanks!

I use geant4.10.07.p02


if thermal neutron elastic scattering is enabled this is normal.


Why?The change of neutron kinetic energy is not right.

I replace physiclist with QGSP_BERT, i.e., I delete neutronHP. Then the kinetic energy’s change become right. But it do not include neutron’s nuclear reaction I want.

If you’re dealing with thermal neutrons, then the random thermal motion of the atoms in your target is important, and can affect the energy a neutron picks up, or loses, in scattering. You are no longer dealing with a high energy beam incident on essentially at-rest target; instead, both the beam (neutron) and target (atom) are moving.

I am having challenge implementing Physics list with QGS_BERT_HP. I am new with Geant4 can some guide me on how I can do this in my PhysicsList and particle gun generation? I really need this and I have struggled for some time now but it is not working.

see examples/extended/hadronic/hadr04 hadr06 hadr07


on top of any reference PhysicsList one can add

myPhysList->RegisterPhysics(new G4ThermalNeutrons());


Dear All,
Am still not able to implement the neutron physics list for low energy neutrons between 0.5 MeV to 5 MeV with the processes indicated in Sallender’s results above elastic, inelastic capture. please I need details of how to go about this in physicsLists and particle generator. I have been trying hard but always get errors. thanks