He3 LEND Cross Sections

Hello all,

I am trying to simulate and compare the responses of He3 and BF3 neutron detectors. I’ve recently switched to using the LEND data set as, from my understanding, they provide the most accurate low energy behavior. I also utilize G4TermalNeutrons to account for low energy scattering in the materials surrounding the detectors to appropriately model their moderation prior to detection. I am currently using my own physics list (PhysicsList.cc), and I score the neutrons with G4PSEnergyDeposit and appropriate filters for the produced ions (tritons, protons, alphas, etc.).

I am seeing some interesting responses from the He3 detector where there are no captures inside the He3 gas with no tritons produced and therefore no 760 keV peak. When I switch to a reference physics list, e.g. QGSP_BIC_HP, I do see many more counts in the detectors with the appropriate capture peak at, however the total number of events is about 30% lower than some previous work has shown it should be for the geometry I am testing, which is why I switched to LEND. Additionally, when I switch to using the BF3 gas with the LEND data set I see the response as expected with the capture peaks at 2.3 and 2.7 MeV and reasonable numbers of events, so it appears the only issue is when He3 is used.

I stumbled across a post recently concerning inaccurate mass values of ions in the LEND data files (Incorrect output energy using LEND), which I fixed to get the appropriate BF3 response, and I assumed it was a similar situation in the He3. After looking through the data files however, I can’t find any other errors and all of the cross sections appear correct based off of ENDF-VII. Does anyone know if there is an issue I may be missing with the LEND data or if there is some other known discrepancies between LEND and QGSP? I am using G4 v11.0.2 and have recreated this on Mac OS as well as Ubuntu. I’d be happy to provide any other information that would be useful as well, I was just hoping to keep this concise.

Any help would be greatly appreciated!

PhysicsList.cc (4.6 KB)