# Simultaneous SAXS/SANS Method at D22 of ILL: Instrument Upgrade
## 4 Conclusions  
A customized SAXS system was successfully installed and operated in combination with the D22 SANS instrument of ILL, resulting in simultaneously collected SAXS and SANS data of the same part of a sample. Due to high-energy gamma radiation inside the D22 instrumental zone, the SAXS instrument was upgraded with a double-energy threshold detector and optimized lead shielding. Background suppression factors were evaluated for different collimation lengths and \(\mathrm{SDD_{X-ray}}\). Extreme background reduction by factors up to 505 was achieved for short collimation lengths and \(\mathrm{SDD_{X-ray}}\). Acceptable signal-to-background ratios of the SAXS patterns comparable to SAXS data collected in the absence of gamma background radiation could be achieved. For long neutron collimation lengths of up to 17.6 m and long \(\mathrm{SDD_{X-ray}}\), the SAXS profiles did not exhibit an increase in background at all when compared to a typical lab experiment. An increase of the corresponding low background by factors of 4 and 8 were observed for neutron collimation lengths of 8 m and 5.6 m, respectively. In the latter experimental configurations, SAXS data of selected test samples prove the suitability of the SAXS instrument for combined SAXS/SANS experiments. The upgraded SAXS system is now compatible with all collimation settings  
Figure 5: Solvent subtracted SAXS/SANS intensity profiles of 100 nm (**a**) and 26 nm (**b**) silica NPs acquired in a simultaneous mode. A common structural model is used for each sample to simultaneously fit both SAXS and SANS data collected from the same sample volume.  
of the D22 SANS instrument, enabling in situ and operando simultaneous SAXS/SANS measurements for a variety of complex nanoscale sample systems.  
Conceptualization, T.U., C.B., K.G., T.Z., L.P.; methodology, E.M., K.G., T.Z., L.P., I.S., C.B., A.M.; data curation, E.M., I.S.; formal analysis, E.M., I.S.; writing--original draft preparation, E.M.; writing--review and editing T.U., L.P., A.M., I.S.; technical details, C.B., E.M., T.U., L.P.; funding acquisition, T.U. All authors have read and agreed to the published version of the manuscript.  
This research is primarily funded by the Federal Ministry of Education and Research of Germany (BMBF) in the framework of project No. 05K16 WE1. As well, this research received funding from the Deutsche Forschungsgemeinschaft (DFG) through the 'Cluster of Excellence Engineering of Advanced Materials (EAM)', the research training group GRK 1896 'In-situ Microscopy with Electrons, X-rays and Scanning Probes' and the research unit FOR 1878 'Functional Molecular Structures on Complex Oxide Surfaces'.  
Not applicable.  
Data Availability Statement: Data presented in this study can be obtained from the authors upon request.  
We gratefully thank [PERSON] (ICSP), [PERSON] (ISCP), [PERSON] (ILL) for their technical support. We acknowledge ILL for the beamtime DOI:10.5291/ILL-DATA.LTP-9-9.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} SDD\({}_{\text{X-ray}}\) & Sample-to-detector distance of SAXS \\ SDD\({}_{\text{Neutron}}\) & Sample-to-detector distance of SANS \\ SLD & Scattering length density \\ col & Neutron collimation \\ diff & Difference mode of double-energy threshold X-ray detector, 4-10 KeV \\ th1 & A single-energy threshold mode of X-ray detector, 4 KeV \\ SD1 & Sample-to-detector distance of SAXS at 0.55 m \\ SD2 & Sample-to-detector distance of SAXS at 1.632 m \\ shield & Lead shielding on the SAXS system \\ NoShield & SAXS system without any lead shielding walls \\ \end{tabular}