I am trying to generate neutrons from bombarding a 5 MeV proton beam on a beryllium target.
I have tried many different physics lists such as FTFP_BERT, QGSP_BERT, and QBBC, etc.
None of the lists gives me good enough neutron kinematics compared with measurements. In particular, with a 1 mA proton beam on beryllium, I am expecting 3e12 neutrons.
However, I only get 1/4 neutron flux with the QBBC physics list, which is already the list with the most generated neutrons.
Would experts here recommend a physics list, or an example for me to generate neutrons that best match measurements?