Photonuclear physics modeling in the MCNPX-PoliMi code

The MCNP-PoliMi code is an enhanced version of the MCNP4c code developed in 2003 to simulate the detector response from correlated neutron and gamma-ray measurements. In 2012 the -PoliMi modifications were incorporated into version 2.7.0 of the MCNPX code. This allows the user to use all of the -PoliMi enhancements in conjunction with the advanced features of the MCNPX code. The MCNPX-PoliMi code has the ability to generate a source file containing the reaction data of all photonuclear reactions occurring in the target material. In addition, a variance reduction option has been implemented whereby the user can read the photonuclear source file multiple times. MCNPX-PoliMi also contains experimentally based models of delayed-neutron emission from photofission reactions. The results presented in the full paper will provide a demonstration of the features of the MCNPX-PoliMi code for active-interrogation scenarios of interest. In particular, the response from uranium will be compared to that of common benign materials.