The GISANS instrument at the HBS

This manuscript describes a concept of a grazing incidence small-angle neutron scattering (GISANS) instrument for the high brilliance source (HBS). The HBS being a compact pulsed neutron source using a moderate energy proton accelerator which allows for very compact moderators and shielding, and flexible pulse repetition rates. Similar to many other instrument concepts for this source, the lowest proposed HBS pulse frequency of 24 Hz with a relatively large detector distance is the optimal choice for the instrument described here in terms of obtained intensity and Q-range (i.e. scattering vector range). Such a configuration has the added advantage of good Q-resolution, which is important when scattering depths need to be resolved well. This is especially the case for GISANS when the incident angle is close to the critical angle of total reflection. The performance obtained from detailed ray-tracing computer simulations predict a high performance instrument that will be comparable to reflectometers and small angle neutron scattering (SANS) instruments at high-flux reactor sources such as the Forschungsreaktor Munich (FRM-2) and others.