PortGISANS: nested mirror optics for a portable GISANS adapter.

Grazing-incidence scattering techniques are powerful tools for studies in surface science. In particular, grazing-incidence neutron scattering (GISANS) provides unique insights in soft-matter systems and magnetic structures, in particular, if they are buried beneath a surface. However, the brilliance of neutron sources is limited hindering the method from becoming widely used. Here we present focusing nested mirror optics that improve the GISANS capabilities of SANS beamlines. Our device preserves the lateral resolution along an interface and relaxes the resolution out-of-plane, sacrificing depth-resolution. By combining ray tracing simulations with the distorted wave born approximation we show that a portable and easy to install optics increases the flux available for GISANS studies, at least, by one order of magnitude and enables straight forward experiments from free liquid surfaces.