## 4 Conclusions  
The low intensity of typical samples in GISANS experiments in the field of soft matter and biology requires thorough experimental planning, data reduction and data interpretation. On the experimental side, the sample cell is a crucial part of the experiment. It has been shown that not only the side of the detector containing the reflected beam and the GISANS data, but also the backside with the transmitted beam contains valuable information and helps understanding different contributions to the signal and to the background. The small-angle scattering signal, i.e., the form factor of the monolayer of microgels present around the transmitted beam, contributed in the current experiment to a background which is not flat. The evaluation in Ref. [11] has been done without such a contribution and showed a significant deviation between measured data and optimal fitting curve with an Ornstein-Zernike model. The gain provided by simulating this SANS contribution with BornAgain provides a means of taking this into account for the interpretation of the GISANS images. Taking into account this additional background which also extends into the upper half of the detector above the horizon of the scattering plane is important if low intensities are evaluated. Soft matter GISANS experiments suffer in many cases from low intensity and rather blurred features on the detector, making this kind of analysis necessary.  
The BornAgain simulation software is a very valuable tool for assessing the background contributions. This has been shown here for GISANS of microgel particles at the  
Figure 5: **Left**: Detector image of microgels at interfaces with the new cell: the GISANS part (left side of the detector) and the SANS part around the transmitted beam (within green frame). **Right**: Line cuts of the detector images along \(q_{z}\) at \(q_{y}~{}=~{}0\) (black line), compared to the data measured with Al cell (red line). A significantly reduced background signal is obtained. The radially averaged SANS intensity of the right side of the detector is shown as blue squares with a fit with an Ornstein-Zernike contribution.  
solid interface, and also helped in understanding background contributions for GINSES experiments (see Ref. [24]).  
Testing a sample cell design with very little amount of material for GIGANS showed very promising results in terms of a reduced background from the sample cell. This design would in principle also allow for new scan mode for GINSES experiments in the q\({}_{y}\) plane to study dynamics, e.g., diffusive processes parallel to the interface.  
Grazing Incidence Neutron Scattering provides unique information on the structure and also on dynamics at interfaces. It is a challenging work to study such small amounts of material as it is common for soft matter samples, but if the necessary care is taken concerning experimental background considerations and parallel simulation of the experiment, valuable information on the interface structure can be obtained.  
conceptualization, T.K., O.H., S.W., J.W., A.F. methodology, O.H.; software, M.G.; formal analysis, T.K.; writing--original draft preparation, O.H., T.K.; writing--review and editing, S.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Deutsche Forschungsgemeinschaft (DFG) (grant Nos. HO 5488/2-1 (OH) and WE 5066/3-1 (SW)).  
Data presented in this study can be obtained from the authors upon request.  
The authors gratefully acknowledge the financial support provided by JCNS to perform the neutron scattering measurements on the KWS-1 and KWS-2 instruments at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany. Fruitful discussion with [PERSON] is acknowledged.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} MDPI & Multidisciplinary Digital Publishing Institute \\ DOAJ & Directory of open access journals \\ TLA & Three letter acronym \\ LD & Linear dichroism \\ \end{tabular}