The NCD beamline, now NCD-SWEET, devoted to Small Angle and Wide Angle X-ray Scattering (SAXS, WAXS), is offering users further experimental possibilities and higher quality data.

Cerdanyola del Vallès, 13th March 2018. The SAXS beamline of ALBA has gone through a major upgrade in 2017. Upgraded items in the SAXS WAXS experimental techniques (SWEET) involve a new monochromator system, a new photon counting detector (Pilatus 1M), a new sample table with an additional rotating stage, and a beam conditioning optics with µ-focus and GISAXS options.

The original double crystal monochromator (DCM) has been replaced by a channel-cut silicon (1 1 1), improving the beam stability at sample position up to 0.9% and 0.4% of the beam size horizontally and vertically, respectivelly.


Figure 1:  Zoom parameters of the on-axis camera

The Be lenses can be set into the beam within few minutes on request. The size of the focused beam at the sample is 2.6 x 2.5 µm2 (H x V) at 12.4keV and the corresponding flux is 2.8 1011 ph/s at 150 mA.


Figure 2: Vertical beam profile with the Be lenses into the beam (Horizontal axis unit is mm). The plot is the derivative of an edge scan along the vertical direction. The horizontal beam profile shows a gaussian shape as well. 

A sample table, produced in-house, has been installed. It has high resolution, vertical (0.39 µm) and pitch (0.54 µrad) motions and can sustain weight up to 100 kg. In addition, there are three sample stages with improved resolution that provide a higher degree of flexibility in the sample environment installation.

The NCD-SWEET beamline is currently offering simultaneous SAXS/WAXS data collection. A new SAXS detector (Pilatus1M) from Dectris (Switzerland) reaches a maximum rate of 25 images/s. 


Figure 3: Picture of the SAXS and WAXS detectors on the NCD-Sweet beamline (left and right, respectively). Image of a polymer collected on the Pilatus detector (middle).

A new technique is now available, GISAXS (Grazing, Indicent SAXS). The first test, performed in December 2017, gave excellent results. The technique will be open to academic users during the call 2018-II.


Figure 4: Data collected on 2 samples during the test on December 2017. The colour scale is logarithmic ranging from 1 to 3000 (left) and 100000 counts/s (right).

Data acquisition and primary reduction in NCD is automated and has a user-friendly interface. The Sardana platform, developed in Python, offers complete remote beamline handling to users as well as easy installation of external experimental environments during experiments. An in-house developed GUI using PyFAI (ESRF, Grenoble) is used for on line data reduction during data collection.


Figure 5: Screenshot of the monitor displaying the data radially averaged for SAXS and WAXS during data collection.

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