|BM26B experiments cabin Photo: Daniel Michon, ARTECHNIQUE|
BM26B is dedicated to SAXS/WAXS measurements. The small-angle and wide-angle patterns can be acquired simultaneously using Two Pilatus photon counting area detectors
SAXS images are collected using a Pilatus 1M detector (169mm x 179mm active area) giving a time resolution down to a few msec/frame. The minimum q-value attainable with our maximum 7m sample-to-detector distance and a photon wavelength of 1.54 Å is about 0.0175 nm-1 (equivalent to a real-space d = 500 nm). The minimum SAXS detector distance is 1.3m
WAXS patterns are collected using a 300K-W linear Pilatus detector ( 254mm x 33.5mm active area). The maximum diffraction angle is about 2Ɵ = 40 °.
If required, a SAXS/WAXS setup without gap between the two measured patterns is possible.
SAXS/WAXS setup on BM26B. The WAXS detector (300K-W) is in the foreground; SAXS (1M) detector is inside the vacuum tube 7m away
The low angle resolution of the SAXS station is dependent on the X-ray wavelength and the sample-to-detector distance.
Spatial resolution; beam size on the sample
The beam size can be tuned from few millimeters down to about 300 x 300 micrometers in standard configurations.
Post-focusing systems are available in order to achieve a smaller beam size.
A heavy-duty '2+3' type diffractometer (combined '2+2' and 'z-axis') allowing horizontal and vertical sample orientation for interface and surface diffraction experiments is mounted in the same hutch.
A great variety of sample environment is available or can be installed on the beam line.
Data are normalised for the incident beam intensity using an in-air ionization chamber and the sample transmission is measured using a pin-diode integrated in the lead beamstop. These values are usually stored in the header of the edf or hdf5/nexus data files provided to the users.
Links and Documentation
For a presentation of the SAXS basic theory, techniques and applications, you can download the book Small Angle X-ray Scattering (O. Glatter and O. Kratky Eds., Academic Press, 1982) from http://physchem.kfunigraz.ac.at/sm/ (Scattering Methods at the Chemistry Department, University of Graz).
For a more biologically oriented introduction one can download Structure Analysis by Small-Angle X-Ray and Neutron Scattering (L. A. Feigin and D. I. Svergun, Plenum Press / Springer, 1987) from http://www.embl-hamburg.de/biosaxs/publications.html
From a practical point of view, you might want to take a look at the Beamline Manuals page. We have posted a short Users' survival manual, the full manual for the data acquisition and reduction software for collecting and pre-processing SAXS and/or WAXS data for both static and time-resolved measurements on beamline BM26B, as well as a list of basic Unix commands.
Last but not least, the Data Reduction and Analysis page provides the response of the detector in use, together with links to data reduction and analysis software.
To estimate your sample absorption click here.