MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich
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Lichtenbergstr.1
85748 Garching

KWS-3

Very small angle scattering diffractometer with focusing mirror

KWS-3 scheme KWS-3 scheme

KWS-3 is a very small angle neutron scattering (VSANS) instrument running on the focussing mirror principle. The principle of this instrument is a one-to-one image of an entrance aperture onto a 2D position sensitive detector by neutron reflection from a double-focussing toroidal mirror.

The instrument’s standard configuration with a 9.5 m sample-to-detector distance allows performing scattering experiments with a wave vector transfer resolution between 4.0·10-5 and 2.5·10-3 Å-1, bridging a gap between Bonse-Hart and pinhole cameras. A second sample position at 1.3 m sample-to-detector distance extends the Q-range of the instrument to 2.0·10-2 Å-1 and reaches more than one-decade overlapping with the classical pinhole SANS instruments. Another “mobile” sample position can be installed to adept sophisticated sample environment between 8 and 2 m sample-to-detector distance according to the requested instrumental resolution.

The instrument covers the Q range of small angle light scattering instruments. Especially when samples are turbid due to multiple light scattering, V-SANS gives access to the structural investigation. Thus, the samples do not need to be diluted. The contrast variation method allows for highlighting of particular components.
Small-angle scattering is used for the analysis of structures with sizes just above the atomic scale, between 1 and about 100 nm, which can not be assessed or sufficiently characterised by microscopic techniques. KWS-3 is an important instrument extending the accessible range of scattering angles to very small angles with a superior neutron flux when compared to a conventional instrumental set up with pinhole geometry. Thus, the length scale that can be analysed is extended beyond 10 μm for numerous materials from physics, chemistry, materials science, and life science, such as alloys, diluted chemical solutions, and membrane systems.

Typical Applications
  • High-flux bridge between Bonse-Hart and conventional SANS diffractometers
  • Colloid science: mixtures of particles, particles of micron size, silicon macropore arrays
  • Materials science: filled polymers, cements, microporous media
  • Polymer science: constrained systems, emulsion polymerisation
  • Bio science: aggregations of bio-molecules, protein complexes, crystallisation of proteins
  • Hierarchical structures
  • Multilamellar vesicles
Sample Environment
  • Anton-Paar fluid rheometer
  • Stopped flow cell
  • Sample holders:
    • 4 horizontal x 2 vertical (temperature controlled) for standard Hellma cells 404-QX
    • 9 horizontal x 2 vertical (room temperature) for standard Hellma cells 404-QX
  • Oil & water thermostats (typical 10 – 100°C)
  • Electric thermostat (RT – 200°C)
  • 6-positions thermostated (Peltier) sample holder (-40 – 150°C)
  • Magnet (2 T, vertical)
  • Magnet (5 T, horizontal)
  • Cryostat with sapphire windows
  • High temperature furnace
  • Pressure cells (500 bar, 2000 bar, 5000 bar)
Technical Data

Overall performance

  • Resolution:
    • δQ = 10-4 Å-1 (extension to 4·10-5 Å-1 possible)
  • Q-range:
    • 1.0·10-4 – 3·10-3 Å-1 at 9.5 m distance
    • 1.5·10-3 – 2·10-2 Å-1 at 1.3 m distance
  • Neutron flux:
    • high-resolution mode: > 10000 n s-1
    • high-intensity mode: > 60000 n s-1

Monochromator

  • MgLi velocity selector
  • Wavelength spread Δλ/λ = 0.2
  • Wavelength range λ = 10 - 30 Å (maximal flux at 12.8 Å)

Aperture size (focus)

  • 1 × 1 mm2 – 5 × 5 mm2

Beam size at 9.5 m

  • 0 × 0 mm2 – 100 × 25 mm2

Beam size at 1.3 m:

  • 0 × 0 mm2 – 15 × 10 mm2

Instrument Scientists

Dr. Vitaliy Pipich
Phone: +49.(0)89.289.10710
E-Mail:

Dr. Zhendong Fu
Phone: +49.(0)89.289.10716
E-Mail:

KWS-3
Phone: +49.(0)89.289.14873

Operated by

JCNS

Gallery

Principle of KWS-3
Principle of KWS-3

The principle of KWS-3 instrument is a one-to-one image of an entrance aperture onto a 2D position sensitive detector by neutron reflection from a double-focusing toroidal mirror; (right) photo of the mirror installed in vacuum its chamber. Length scales up to 10 μm are accessible.

Measurement of polystyrene spheres
Measurement of polystyrene spheres

Polystyrene spheres of 7600 Å diameter measured at 9.5 and 1.2 m at KWS-3 (black symbols: concentration of spheres in water 0.2wt %). The red curve is the theoretical scattering curve (form factor of 7600 Å spheres). The instrumental resolution and sample polydispersity were not taken into account. Mismatching of the measured curve and model at low Q is due to the presence of the structure factor.

KWS-3
KWS-3

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich