We consider neutron interaction with targetmaterial germanium, particularly the non-ionising energy loss (NIEL) of the neutrons (which is dependent on the number and energy of the generated recoils). We notice discrepancies in the statistics of inelastic recoils (residual nuclei) when compared to expected values and when switching from neutron_HP to binary cascade at 20 MeV. These discrepancies persist after deleting the Ge-isotope data files in "G4NDL3.7/Inelastic/CrossSection" (workaround for bug #526 to prevent the usage of gallium-data). After using a modified "G4NeutronHPInelasticComp.cc", which should take care of the conservation of linear momentum (bug #675) and has been kindly provided by Joa Ljungvall, the recoil energy is closer to what is expected, but with increasing neutron energy (< 20 MeV) our NIEL results get worse. It turned out that there is a correlation with the contribution to final states from Ge(n,2n)Ge reactions, which -according to the data in "/F04" compared to "/F01"- increases with increasing neutron energy. It seems that no residuals are generated for Ge(n,2n) reactions. This is probably not the intended behaviour of neutron_hp. PS: We initially suspected a mix-up or corruption of cross-sections due to a faulty file reading or invalid memory pointers and coarsely checked the file reading and the memory usage. Indeed we observe that in G4NeutronHPPartial::InitData() the allocated data space is exceeded when neg>nData.
Thank you for reporting problem. This is under invetigation. If you have any updated information, please let me know. Tatsumi
This problem is identified and a temporal fix will be released soon. However the fix is not guaranteed conservation laws at single event level. Tatsumi
The recoil (residual) nucleus should exist in final state. Energy and momentum conservation is not guaranteed at single event level. This is a kind of model feature. However if you have very big difference in binary reaction (ex elastic, nA-pB and so on), please let me know. I changed status of this entry to “RESOLVED-FIXED”. Tatsumi
