Calculation of neutron response functions in complex geometries with the MCNP code

For the analysis of (e,én) coincidence experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC, neutron response functions of NE 213 liquid scintillation detectors had to be calculated. We report, for the first time, on calculations of neutron response functions with a modification of the MCNP code taking into consideration nonlinear light output functions for secondary charged particles. The code was tested for a simple detector geometry against the widely used NRESP code. Excellent agreement between results of NRESP and MCNP calculations was achieved for neutron energies up to 8 MeV when the same detector model, light output functions and neutron cross sections were used. With this modification of the MCNP code, the response functions can now be determined for arbitrary complex detector arrangements, e.g. including massive shieldings.