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85748 Garching

KWS-3 ‚VerySANS‘

Very small angle scattering diffractometer with focusing mirror

This instrument is focussed on cold neutrons. All parameters given here are valid during the current operation of FRM II. Please get in touch with the instrument team well in advance for all further details (length of experiment etc.).

Instrumentscheme KWS-3 Instrumentscheme KWS-3

KWS-3 is a very small angle neutron scattering (VSANS) instrument running on the focusing mirror principle. The instrument is designed to bridge the gap between Bonse-Hart and pinhole cameras. Some details of the diffractometer operation are explained in fig. 1 (see gallery): 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-focusing toroidal mirror.

The instrument’s standard configuration “VSANS” with a 9.3 m sample-to-detector-distance (SDD) and 2 × 2 mm2 entrance aperture (EA) allows performing scattering experiments with a wave vector transfer resolution between 1.0 · 10-4 and 2.5 · 10-3 Å-1.

‘VerySANS’ is a focusing instrument. Unlike at a pinhole SANS instrument, we can not improve the dynamical range (Qmax/Qmin) by moving the detector: the position of the KWS-3 detector is fixed in the right focus as shown in fig. 1. At KWS-3, we extended the dynamical range by ‘replicating’ of the sample positions at different distances between the sample and the detector. Such kind of ‘Multi-sample-position-approach’ (fig. 2) is completed in 2021.

Compact sample environment (SE) (gallery, tab. 1 and fig. 3a): We can install a compact SE (volume below 30 × 30 × 30 cm3) inside two vacuum chambers located at SDD = 9.3 and 1.7 m; as well as those samples can be measured in the close vicinity of the detector (SDD = 0.05 – 0.40 m). In tab 1, all parameters of configurations in case of the compact SE are listed. The combination of several configurations, called “USANS”, “VSANS”, “SANS-overlap” and “SANS” allows performing scattering experiments with a wave vector transfer resolution between 3.5 · 10-5 and 3.5 · 10-1 Å-1, covering four decay of the dynamical range.

Bulky sample environment (SE) (gallery, tab. 2 und fig. 3a): In the current instrument configuration, we can install a bulky SE at SDD = 10, 4, 3, and 2 m. At these positions we can precisely positioning as well rotate and tilt a sample together with a bulky/ heavy SE. A sample in a few Tesla magnetic field or under shear in the rheometer can be measured within q-range between 3.5 · 10-5 and 10-2 Å-1.

The instrument covers the Q range of small angle light scattering instruments. Especially when samples are turbid due to multiple light scattering, VSANS 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 cannot 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 setup 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
  • Aggregation in colloidal dispersions
  • Self-assembling of polymers
  • Hierarchical structures of biominerals
  • Hydrogels and aerogels
  • Membrane systems
  • Rheology and structure/morphology of complex fluids
  • Morphology of vortex lattice domains
  • Surface and interface structure
  • Porous structure & gas storage in rocks
  • In-situ study of solid phase transition/crystallisation at high temperature
  • Colloid science: mixtures of particles, particles of micron size, silicon macropore arrays
  • Materials science: filled polymers, cements, microporous media
  • Polymer science: constrained systems, emulsion polymerization
  • Bio science: aggregations of bio-molecules, protein complexes, crystallisation of proteins
  • Multilamellar vesicles
  • Neutron polarisation & polarisation analysis
Sample Environment
  • Anton-Paar fluid rheometer
  • Stopped flow mixer with UV-Vis and fluorescence detector
  • Different RT-sample holders
  • Oil & water thermostats (typical 5 – 150°C)
  • Electric thermostat (RT – 200°C)
  • 6/8-positions Peltier sample holder (-10 – 150°C)
  • Magnet (2 T, vertical)
  • Magnet (3 T, horizontal)
  • Cryostat with sapphire windows
  • High temperature furnace (RT – 2000°C)
  • Pressure cells (500 bar, 2000 bar, 5000 bar)
  • Humidity generator and humidity cells (0 – 90 RH %)
  • Linkam Modular Force Stage (tensile testing at various temperature and humidity)
Technical Data
Monochromator
  • MgLi velocity selector
  • Wavelength spread Δλ/λ = 0.17
  • Wavelength range λ = 10.5 – 30 Å (maximal flux at 12.8 Å)
Entrance aperture size
  • 0 × 0 – 10 × 10 mm2
  • 0.7 × 0.7 mm2 (“USANS” modes with VHRD)
  • 2.0 × 2.0 mm2 (“VSANS” and “SANS” modes with HRD: “high resolution” mode)
  • 4.0 × 4.0 mm2 (“VSANS” and “SANS” modes with HRD: “high intensity” mode)
Detectors
  • HRD:
    • Type: Scintillator, 6Li, 1 mm
    • Active area: ∅ 9.0 cm
    • Pixel size: 0.34 : 0.34 mm2
    • Dead-time: 2.9 μs
    • Matrix Dim.: 256 × 256
  • VHRD:
    • Type: Scintillator, 6Li, 1 mm
    • Active area: 3 × 3 cm2
    • Pixel size: 0.12 : 0.12 mm2
    • Dead-time: 2.7 μs
    • Matrix Dim.: 256 × 256
Q-range:
  • 3.5 · 10-5 – 3.5 · 10-1 Å-1 (Compact SE, tab. 1)
  • 3.5 · 10-3 – 1.2 · 10-2 Å-1 (Bulky SE:, tab. 2)
Sample
  • Several samples measured at KWS-3 are shown in fig. 3b (see gallery)
  • All possible instrument configurations are listed in tab. 1 and 2 (see gallery)
  • “USANS”, “USANS-10m” and “SANS” configurations:
    • currently only very strongly scattering samples can be measured
  • simulated intensity of “VSANS” and “SANS-overlap” configurations
    • 1200 n s-1 (in “high resolution” mode with EA = 2 × 2 mm2)
    • 4800 n s-1 (in “high intensity” mode with EA = 4 × 4 mm2)

Instrument Scientists

Dr. Vitaliy Pipich
Phone: +49 (0)89 158860-710
E-Mail: v.pipich@fz-juelich.de

Dr. Baohu Wu
Phone: +49 (0)89 158860-687
E-Mail: ba.wu@fz-juelich.de

KWS-3
Phone: +49 (0)89 158860-513

Operated by

JCNS

News

KWS-3: More flexible for users

KWS-3: More flexible for users

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ERuM Pro Project NHSM

ERuM Pro Project NHSM

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Publications

Find the latest publications regarding KWS-3 in our publication database iMPULSE:

impulse.mlz-garching.de

Citation of the instrument

Heinz Maier-Leibnitz Zentrum. (2015). KWS-3: Very small angle scattering diffractometer with focusing mirror. Journal of large-scale research facilities, 1, A31. http://dx.doi.org/10.17815/jlsrf-1-28

For citation please always include the DOI.

Gallery

Tab. 2: Configurations with buky sample environment 8 SE)
Tab. 2: Configurations with buky sample environment 8 SE)

We define SE as “bulky” if we can not position it inside the vacuum chambers. For example, 2 T electromagnet or Anton-Paar rheometer are too big and/or too heavy to be inserted into the vacuum chambers located at SDD = 9.3 and 1.6 m. The weight of any bulky SE is limited to 500 kg and its dimensions to 70 × 70 cm2.

Like in tab. 1: We propose to our users also “high intensity” configurations with relaxed resolution with 4 × 4 mm2 entrance aperture instead of 2 × 2 mm2. The dynamical range is around 12 instead of 25. The intensity of all “VSANS” configurations is four times higher after “relaxing” of the resolution.

Tab. 1: Configurations with compact sample environment (SE)
Tab. 1: Configurations with compact sample environment (SE)

Compact sample environment is suitable for the vacuum chambers. Thus, the volume is limited to about 30 × 30 × 30 cm3. All room temperature sample holders, oil/water thermostats, electric thermostat, 6/8-positions Peltier sample holders and pressure cells are suitable for vacuum chambers and above listed configurations.

These are configurations with optimized entrance aperture to the detector resolution (with maximal dynamical range): for HRD detector the optimal entrance aperture is 2 × 2 mm2 and for VHRD detector the optimal entrance aperture is 0.7 × 0.7 mm2. We call them “high resolution” configurations. We propose to our users also “high intensity” configurations with relaxed resolution with 4 × 4 mm2 entrance aperture instead of 2 × 2 mm2: the dynamical range is around 12 instead of 25. The intensity of “VSANS”, “SANS-overlap” and “SANS” configurations is four times higher after “relaxing” of the resolution.

Fig. 3b: Q-range map of KWS-3
Fig. 3b: Q-range map of KWS-3

Several samples measured in different configurations of KWS-3.

Fig. 3a: Q-range map of KWS-3
Fig. 3a: Q-range map of KWS-3

Q-range presentation of the KWS-3 configurations for a compact (tab. 1) or bulk (Tab. 2) sample environment. At the moment, we advise to use “USANS-10m”, “USANS” and “SANS” configurations only for strongly scattering samples.

Fig. 2: Multi-sample-position-approach
Fig. 2: Multi-sample-position-approach

a) Multi-sample-position-approach evolution of KWS-3 instrument is completed in 2021: compact sample environment can now be installed at SDD = 9.3, 1.7 and 0.4 – 0.05 m; bulky sample environment can now be installed at SDD =10, 4, 3 and 2 m.
b) The ‘tube with box’ installed at SDD = 2 m: if the sample position at SDD = 2 m is not used (like here), the space inside the box is filled by tubes (vacuum inside).
c) The ‘tube with box’ installed at SDD = 2 m: 2 T electromagnet installed inside.

Fig. 1: Instrument principle
Fig. 1: Instrument principle

The shape of the focusing mirror is toroidal (quasi-ellipsoidal); a) meridional radius (531 m) of the mirror defines the length of the instrument to the value of the focus-to-focus distance of the ellipse (near 22 m). In the “left” focus, the entrance aperture (EA) that defines the instrument resolution is placed; the mirror b) reflects all neutrons to the “right” focus, where the detector is fixed. Length and width of the mirror (120 × 12 cm2) limit the maximal beam size just after the mirror. We use the maximal sample aperture behind the mirror, 80 × 20 mm2. c) 16 cm2 beam is focused on the detector in several square millimeters. The mirror geometry also determines the used wavelength range. The instrument has a maximum intensity at  = 12.8 Å where the total surface of the mirror is below the critical angle and reflects almost 100 % of the neutrons. In case of 10 Å and 8 Å, the reflectance is below 10 % and 1 % respectively.

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Hereon> Helmholtz-Zentrum Hereon
Forschungszentrum Jülich> Forschungszentrum Jülich

MLZ is a member of:

LENS> LENSERF-AISBL> ERF-AISBL

MLZ on social media: