SAPUCAIA: The SAXS beamline at Sirius

Small-angle X-ray Scattering technique addresses the morphological (shape, size, and spatial organization) and dynamical properties of nano- and micro-structured objects. SAXS is an important technique applied in many branches of science, including physics, chemistry, biology, and engineering. The Sapucaia beamline will be able to tackle a number of significant scientific questions with regard to structural biology (proteins, nucleic acids, lipids, and general macromolecules), life science (biological and medical applications), and a vast area of materials science, including nanotechnology, polymers, and environmental sciences. The beamline will be used to examine both solid and in-solution samples. A significant q-range and X-ray energy window are developed (from 6 to 17 keV). This design was chosen in order to give highly reproducible and low-noise data while keeping the beamline as stable as feasible. The experimental and optical hutches are set up outside the shielding wall and the detector is placed into a tunnel with a 2 m diameter at a low pressure (10-3 mbar). The optical devices are a toroidal mirror that bounces horizontally and a double-crystal monochromator, both housed in the first hutch. They are responsible for the collimation and focalization of the X-ray beam, which in turn arises from an undulator. The primary experimental station is housed in the second hutch and comprises absorbers, a fast shutter, and different sample holders. A 15-meter-long tunnel houses the detector (PiMega 540D), allowing a 2.10-3 to 20nm-1 q-range. Sapucaia will be one of the most significant SAXS beamlines in the world thanks to three crucial aspects that were used to determine the beamline design: minimal parasitic X-ray scattering, small beam divergence, and outstanding optical component stability. As a result, researchers will be able to measure the so-called: Conventional SAXS, Size Exclusion Chromatography-SAXS, and kinetic SAXS, among others.

This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP). This research used facilities of the Brazilian Synchrotron Light Laboratory (LNLS), part of the Brazilian Center for Research in Energy and Materials (CNPEM), a private non-profit organization under the supervision of the Brazilian Ministry for Science, Technology, and Innovations (MCTI).