Validation of Monte-Carlo simulations with measurements at the ICON beam-line at SINQ

ICON is the new cold neutron imaging facility at the neutron spallation source SINQ. The ICON facility is placed at beam-line S52 with direct view to the cold liquid D2 moderator. The beam-line includes a 4.4 m long collimation section followed by a 11 m long flight path to the imaging system. The essential part of the collimation section is composed of six revolving drums and a variable aperture wheel. Depending on the investigated object, different apertures are used. Measurements have shown that each setup has a different spatial neutron flux distribution and specific beam profiles. Measured beam profiles have been used to validate results of simulations coupling the Monte-Carlo program MCNPX with the neutron ray-tracing program McStas. In a first step, MCNPX was used to calculate neutron spectra closed to the SINQ target, at the entrance of the collimation section. These results served as an input for McStas where the beam-line itself was simulated. In the present paper, experimental and theoretical results will be compared and discussed.