Klinkby, Esben Bryndt1; Lauritzen, Bent1; Nonbøl, Erik1; Willendrup, Peter Kjær3; Filges, Uwe7; Wohlmuther, Michael7; Gallmeier, Franz X.8
1 Center for Nuclear Technologies, Technical University of Denmark2 Radiation Physics, Center for Nuclear Technologies, Technical University of Denmark3 Department of Physics, Technical University of Denmark4 Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark5 Paul Scherrer Institut6 Oak Ridge National Laboratory7 Paul Scherrer Institut8 Oak Ridge National Laboratory
Simulations of target-moderator-reflector system at spallation sources are conventionally carried out using Monte Carlo codes such as MCNPX or FLUKA[2, 3] whereas simulations of neutron transport from the moderator and the instrument response are performed by neutron ray tracing codes such as McStas[4, 5, 6, 7]. The coupling between the two simulation suites typically consists of providing analytical fits of MCNPX neutron spectra to McStas. This method is generally successful but has limitations, as it e.g. does not allow for re-entry of neutrons into the MCNPX regime. Previous work to resolve such shortcomings includes the introduction of McStas inspired supermirrors in MCNPX. In the present paper different approaches to interface MCNPX and McStas are presented and applied to a simple test case. The direct coupling between MCNPX and McStas allows for more accurate simulations of e.g. complex moderator geometries, backgrounds, interference between beam-lines as well as shielding requirements along the neutron guides.
Nuclear Instruments and Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment, 2013, Vol 700, p. 106-110