## 3 Summary and Scientific Performance  
The overall goal of SKADI is to cater to a wide range of scientific needs in order to allow for most conceivable small-angle neutron scattering experiments. This is achieved by a versatile sample area, a well adaptable collimation, as well as a high-flux capable detector for single shot experiments of kinetic transitions in samples. This combination of the two techniques is a challenging problem. Figure 9: (**a**) Photograph of a \(2\times 2\) module of a SoNDe type detector. Each tile is \(10\times 10\) cm in size. (**b**) Arrangement of active area tiles, as shown in (**a**) for the complete detector setup. tion should allow excellent experiments, resulting in high-profile scientific investigations and publications. Those capabilities are accompanied by a world leading high flux at sample position and an excellent resolution down to very low Q-values around several times \(10^{-4}\) A\({}^{-1}\) in a pin-hole setting and even lower using the VSANS setup. The upper Q limit is well above \(1\) A\({}^{-1}\), depending on the specific setting. In between those limits, dynamic Q-range of \(Q_{max}/Q_{min}\approx 1000\) are feasible, which makes single shot experiments over a wide range of length scales in the sample feasible. This could be achieved by thoroughly designing SKADI from the neutron extraction to the detector with scientific performance and applicability in mind. This means that each component was first simulated as a standalone setup with a generic neutron flux, until the desired performance criteria where met. Afterwards, the specific component was simulated in tandem with the rest of the instrument and the model of the ESS moderator to assess a realistic scenario. While doing this, the pertinent parameters, such as the m-values of the guides, as well as the length and position of components, were varied in order to make sure the configuration was in a stable performance maximum. The SoNDe detector was finally developed specifically for use in a SANS instrument [7; 18; 19; 20]. Summarizing this procedure, for SKADI there are a few key properties of such a SANS instrument at a high brilliance spallation source, such as the ESS. Starting at the neutron extraction, with the necessity to displace the primary beam in order to avoid a direct view of the moderator from the sample position, the general approach of using a long curved guide would have resulted in either a very long bunker or an extremely poor transmission. This can be mitigated using a channeled bender, but the technical limitations on lifetime in a hard radiation environment and reflectivity strongly limit that approach. Additionally, mostly short wavelength and high divergencies profit from such a setup, which are not the most profitable neutrons to transport for a SANS experiment. Using the deflector setup, a twice reflected direct image of the moderator can be transported. By choosing the angles and coating appropriately, even a low wavelength cutoff can be obtained, which is both beneficial for the experiment itself, as well as shielding of the rest of the instrument. Continuing to the chopper setup, it is clear that a time of flight instrument needs at least two choppers to define the wavelength band and prevent the frame overlap from secondary neutrons. The acceptable wavelength band is defined by the farthest detector position, and an optimal position for the first chopper is as far upstream as technically feasible, since this removes background farther from the detector. In combination, those two requirements then also define the position of the second chopper. The high resolution choppers, which still can be installed on SKADI as an upgrade, have advantages, as shown in this manuscript, however are not strictly necessary for a high performance SANS instrument and would be most profitable in the case of weak signals, a problematic signal to noise ratio, or a combination thereof.