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Specifications

 

The insertion device

 
The wiggler for the SAXS beamline consists of three 1.5 m long segments, each having 19 poles. The device can work with a minimum gap of 20 mm, which corresponds to K=20 at 2 GeV. The main parameters of the wiggler are:
 
·      Critical Energy 4.1 keV
·      Radiation Power 8.6 kW
·      Flux 3.5x1014 ph/s/mrad/0.1%BW (at 400 mA)

The wiggler radiation cone has a horizontal width of 9 mrad. From this the SAXS-beamline accepts vertically 0.3 mrad, and horizontally +/-0.5 mrad at a 1.25 mrad off-axis position. The resulting source size for 8 keV photons is 3.9 x 0.26 mm2 (horiz. x vert.).

The beamline optics

 
The optics common with the diffraction beamline consists of:
·      Carbon-Filter to reduce the power load on the first optical elements by a factor of 2
·      Beryllium windows to separate the beamline vacuum from the storage ring
·      Beam defining slit chamber before the SAXS monochromator
 
The SAXS beamline optics consists of:
·      A double-crystal monochromator
·      A baffle chamber after the monochromator is used as an adjustable straylight fenditure
·      A segmented toroidal mirror focuses the light in horizontal and vertical direction with a 1/2.5 magnification onto the SAXS-detector
·      An aperture slit reduces the straylight after the monochromator and the toroidal mirror
·      A guard slit defines the illuminated region on the sample



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 and colloids
·      Liquid Crystals
·      (Bio) Polymers
·      Amorphous Materials
·      Muscles
·      Proteins
·      Metals, cements, oils
·      Quantum dots
·      and much more ...


Source characteristics


The photons are provided by a Wiggler (NdFeB Hybrid) with the following specifications:

Period: 140 mm
Number of full poles: 57
Gap: 20 mm
Bmax: 1.607 T
Critical Energy Ec: 4.27 eV   (at 2 GeV)
Power (9 mrad): 8.6 kW   (at 2 GeV, 400 mA)
effective source size FWHM: 3.9 x 0.26 mm2(HxV)   (at 2 GeV, 400 mA)

 


Optics

 
Double crystal monochromator:  18.4 m from source, Si (111) asym. cut, water cooled
Focussing mirror: 26.5 m from source, two segments, toroidal, Pt coated
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 possible spot: 10 µm
Flux at sample: 1 x 1013 ph s-1 (2 GeV, 400 mA, 8 keV)
Flux density at sample: 1 x 1012  ph s-1 mm-2  (2 GeV, 400 mA, 8 keV)



Experimental resolution

 
Small angle:
Real space: 1-140 nm 

Wide angle:
0.1- 0.9 nm 


 


Accessible SAXS and WAXS range


Small angle:

Real space: 1-140 nm (8 keV)
                     1-63 nm (16 keV)



Wide angle:

angular region from 17 - 85o  (2Theta)



SWAXS:

Simultaneous SAXS- and WAXS-measurements can be performed using a Pilatus3 1M detector for the SAXS signal, and a Pilatus 100k detector for the WAXS-range.

For transmission experiments, also a specially designed vacuum chamber (SWAXS-nose, see Annual Report of 1996/97, p. 32) can be used which allows to use both scattering areas below (for SAXS) and above (for WAXS) the direct beam, respectively. The overall length of the SWAXS-nose in horizontal direction, measured from the sample position, is 512 mm and the fixed sample to WAXS-detector distance is 324 mm. Therefore, at the shortest SAXS camera-length an overlap in the d-spacings covered by the SAXS- and WAXS-detectors, respectively, is possible: then, the common regime lies around 9 Å (at 8 keV, using for WAXS the 2Theta = 9.4 - 27.6o range).

Last Updated on Monday, 29 April 2019 15:20