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MLZ (eng)

Lichtenbergstr.1
85748 Garching

KWS-1

Small angle scattering diffractometer

KWS-1 scheme KWS-1 scheme

The KWS-1 is dedicated to high resolution mea­surements due to its 10 % wavelength selector. This property is interesting for highly ordered or highly monodisperse samples. With the foreseen chopper the wavelength uncertainty can be reduced further to ca. 1 %. The scientific background of KWS-1 is placed in magnetic thin films. Magnetic samples will be studied with the full polarization analysis including incident beam polarization and polarization analysis of the scattered neutrons. In front of the collimation, a 3-cavity polarizer with V-shaped mirrors is placed. The full bandwidth of 4.5 to 20 Å will be covered with min. 90 % (95 % typical) polarization. A radio frequency spin flipper allows for changing the polarization. The polarization analysis will be realized with 3He-cells which will be optimized for the used wavelength and scattering angle. Vertical magnets will be provided to render the magnetic field at the sample position. Thin films can be well studied in the grazing incidence geometry – the method is called grazing incidence small angle neutron scattering (GISANS). A newly installed hexapod will allow for positioning the sample with 0.01 mm and 0.01° precision.

Classical soft-matter systems will be investigated on KWS-1 if the resolution is needed. Biological samples can be handled due to the detector distance of ca. 1 m, which will allow for maximal scattering angles of Q = 0.5 Å-1.

The MgF2 lenses are used for the high flux mode with large sample areas, while the resolution stays in the classical SANS range. These enhanced intensities allow for real time measurements in the 1/10 second region (typical 1 s).

The chopper in parallel allows for studying faster dynamics in the ms range. The so-called TISANE mode interlocks the chopper frequency with the excitation field frequency and with the detection binning. The precise consideration of the flight times allows for higher precision compared to classical stroboscopic illuminations.

Typical Applications

Grain boundaries

  • Alloys
  • Magnetic structures
  • Flow lines
  • Soft matter and biology (as for KWS-2)
  • Complex fluids near surfaces
  • Polymer films
  • Magnetic films
  • Nanostructured films

One example of a complex fluid near planar sur­faces is discussed in context of figure 1. For enhanced oil recovery often aqueous surfactant systems are used, which, in contact with oil, form microemulsions. The current study focuses on bicontinuous microemulsions adjacent to a planar hydrophilic wall. The surface near structure is lamellar and decays to the bulk structure. Interestingly, this decay is realized by perforated lamellae. Currently, flow experiments are performed.

Sample Environment
  • Rheometer shear sandwich
  • Rheowis-fluid rheometer (max. shear rate 10000 s-1)
  • Anton-Paar fluid rheometer
  • Stopped flow cell
  • Sample holders: 9 horizontal x 3 vertical (temperature controlled) for standard Hellma cells 404.000-QX and 110-QX
  • Oil & water thermostats (typical 10 – 100 °C) electric thermostat (RT – 200°C)
  • 8-positions thermostated (Peltier) sample holder (-40 – 150°C)
  • Magnet (horizontal, vertical)
  • Cryostat with sapphire windows
  • High temperature furnace
  • Pressure cells (500 bar, 2000 bar, 5000 bar)
Technical Data

Overall performance

  • Q = 0.0007 – 0.5 Å-1
  • Maximal flux: 1.5 · 108 n cm-2 s-1
  • Typical flux: 8 · 106 n cm-2 s-1 (collimation 8 m, aperture 30 x 30 mm², λ = 7 Å)

Velocity selector

Dornier, FWHM 10 %, λ = 4.5 Å – 12 Å, 20 Å

Chopper

for TOF-wavelength analysis, FWHM 1 %

Polarizer

Cavity with V-shaped supermirror, all wavelengths
Polarization better 90 %, typical 95 %

Spin-flipper

Radio-Frequency

Active apertures

2 m, 4 m, 8 m, 14 m, 20 m

Aperture sizes

rectangular 1 x 1 mm2 – 50 x 50 mm2

Sample aperture

rectangular 1 x 1 mm2 – 50 x 50 mm2

Neutron lenses

MgF2, diameter 50 mm, curvature 20 mm
packs with 4, 6, 16 lenses

Sample stage

Hexapod, resolution better than 0.01 °, 0.01 mm

Detector 1

Detection range: continuous 1 m – 20 m
6Li-Scintillator 1 mm thickness + Photomultiplier
Efficiency better than 95 %
Spatial resolution 5.3 x 5.3 mm2, 128 x 128 channels
Max. countrate 0.6 MHz (τdead = 0.64 μs)

Instrument Scientists

Dr. Henrich Frielinghaus
Phone: +49.(0)89.289.10706
E-Mail:

Dr. Artem Feoktystov
Phone: +49.(0)89.289.10746
E-Mail:

Dr. Zhenyu Di
Phone: +49.(0)89.289.10705
E-Mail:

KWS-1
Phone: +49.(0)89.289.14324

Operated by

Logo JCNS

Gallery

GISANS pattern
GISANS pattern

GISANS pattern of a microemulsion adjacent to a planar wall. The Bragg peak indicates the lamellar order induced by the wall. A weak Debye-Scherrer ring arises from the bicontinuous bulk structure.

KWS-1
KWS-1

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