Austrian SAXS Beamline Homepage

INTRODUCTION

Small Angle X-ray Scattering has become a well known standard method to study the structure of various objects in the spatial range from 1 to 200 nm, and therefore instruments capable to perform such experiments are installed at most of the synchrotron research centers. This high flux SAXS beamline at ELETTRA is mainly intended for time resolved studies of fast structural transitions in the sub millisecond time region in solutions and partly ordered systems with a design goal of at least 100 nm SAXS-resolution.

The photon source is the 57 pole wiggler whose beam is shared with a Macromolecular Crystallography beamline. The wiggler delivers a very intense radiation between 4 and 25 keV of which the SAXS beamline accepts 3 discrete energies, namely 8 keV, as well as 5.4 and 16 keV. A flat double crystal monochromator and a double focusing toroidal mirror are used as beamline optics. A versatile SAXS experimental station has been set-up with the option to use an additional wide angle X-ray scattering (WAXS)-detector for taking simultaneously diffraction patterns in the range of 0.1 - 0.9 nm. The sample station is mounted moveable onto an optical table for optimizing the sample detector distance with respect to SAXS resolution and sample size. Besides the foreseen sample surrounding the users will have the possibility to install their own specialized sample equipment. In the design phase, besides technical boundary conditions, user friendliness and reliability have been considered as important criteria.

BEAMLINE CHARACTERISTICS

Scientific applications	Low Contrast Solution Scattering, Grazing Incidence Surface Diffraction, Micro-Spot Scanning, X-ray Fluorescence Analysis, Time-Resolved Studies > 11 µs and Simultaneously Performed Small- and Wide-Angle Measurements (SWAXS) on: Gels Liquid Crystals (Bio) Polymers Amorphous Materials Muscles Quantum dots
Source characteristics	Wiggler (NdFeB Hybrid):
	Period No. full poles Gap B_max Critical Energy E_c Power (9 mrad) Effective source size FWHM	140 mm 57 20 mm 1.607 T 4.27 keV 8.6 kW 3.9 x 0.26 mm²(HxV)
Optics	Optical elements:	Double crystal monochromator: Si (111) asym. cut, water cooled.	Mirror: two-segment,toroidal, Pt coated.
	Distance from source:	18.4 m	26.5 m
	Acceptance	1 mrad/0.3 mrad (HxV)
	Energy (3 selectable)	5.4, 8, 16 keV (0.077, 0.154, 0.23 nm)
	Energy resolution deltaE/E	0.7-2.5 x 10^-3
	Focal spot size FWHM	1.2 x 0.6 mm² (HxV)
	Spot at Sample FWHM	< 1.4 x 1.8 mm²(HxV) (using slits or pinhole) Smallest spot possible 10 µm.
	Flux at sample	5 x 10¹²ph s^-1(2 GeV, 200 mA, 8 keV)
	Flux density at sample	5 x 10¹¹ ph s^-1 mm^-2 (2 GeV, 200 mA, 8 keV)
Experimental apparatus	Resolution in real space: 1-140 nm (small-angle), 0.1- 0.9 nm (wide-angle) Sample stage: temperature manipulations: ramps, jumps and gradient scans, pressure manipulation: scan and jumps, flow jump experiments, SWAXS measurements applying mechanical stress, SWAXS measurements applying magnetic fields. Detectors: 1D gas-filled detectors (Gabriel type), 2D CCD-detector (Photonic Science, Robertsbridge, UK).
Experiment control	beamline control: Program-units written in LabView for Windows 1 D detector control: PC-card and software from Hecus X-Ray Systems GmbH, Graz, AT. 2 D detector control: Software from Media Cybernetics (Image-Pro Plus), Silver Springs, USA.

CURRENT STATUS

The beamline has been built by the Institute of Biophysics and Nanosystems Research (IBN), Austrian Academy of Sciences, and is now in user operation since September 1996. The set-up of the beamline started at the beginning of January 1995 with the installation of the support structure. Until the end of 1995, the 8 keV single energy system had been realized. The upgrade to the full three energy system was finished in spring 1998. Time resolved experiments require fast X-ray detectors and data acquisition hard- and software. Depending on the desired resolution in time and in reciprocal space, on isotropic or anisotropic scattering of the sample, one-dimensional position sensitive (delay line type) or two-dimensional area detectors (CCD-type) are employed.

In August 2002 our new chemistry and X-ray laboratory went into operation. The chemistry unit serves mainly for sample preparation and analysis for both, in house research and external user groups, whereas the X-ray laboratory allows on-site testing of samples before moving on to the SR beamline

In conclusion, due to wide tuneability of the beamline and the highly variable kept sample stage, there are nearly no limits for the realization of an experiment, and you are welcome by our team to propose any interesting and high-lighting investigation for the benefit of material and life sciences.