Journal of large-scale research facilities, 1, A31 (2015) http://dx.doi.org/10.17815/jlsrf-1-28 Published: 19.08.2015 KWS-3: Very small angle scattering di�racto- meter with focusing mirror Heinz Maier-Leibnitz Zentrum Forschungszentrum Jülich, Jülich Centre for Neutron Science Instrument Scientists: - Vitaliy Pipich, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany, phone: +49(0) 89 289 10710, email: v.pipich@fz-juelich.de - Zhendong Fu, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany, phone: +49(0) 89 289 10716, email: z.fu@fz-juelich.de Abstract: KWS-3, which is operated by JCNS, Forschungszentrum Jülich, is a very small angle neutron scattering (VSANS) instrument running on the focussing mirror principle. KWS-3 is designed to bridge the gap between Bonse-Hart and pinhole cameras. Owing to its extended Q range, optimized �ux, and good wavelength resolution, KWS-3 has shown good performance and has become scienti�cally productive to the user community. 1 Introduction The principle of this instrument is a one-to-one image of an entrance aperture onto a 2D position sensitive detector by neutron re�ection from a double-focussing toroidal mirror. The instrument’s standard con�guration with a 9.5 m sample-to-detector distance allows perform- ing 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. 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-1-28 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A31 (2015) http://dx.doi.org/10.17815/jlsrf-1-28 Figure 1: Instrument KWS-3 (Copyright by W. Schürmann, TUM). 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 su�ciently 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 �ux 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. 2 Typical Applications • High-�ux bridge between Bonse-Hart and conventional SANS di�ractometers • Colloid science: mixtures of particles, particles of micron size, silicon macropore arrays • Materials science: �lled 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 3 Sample Environment • Anton-Paar �uid rheometer • Stopped �ow 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 °C – 100 °C) • Electric thermostat (RT - 200 °C) 2 http://dx.doi.org/10.17815/jlsrf-1-28 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-1-28 Journal of large-scale research facilities, 1, A31 (2015) Figure 2: Schematic drawing of KWS-3. • 6-positions thermostated (Peltier) sample holder (-40 °C – 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) 4 Technical Data 4.1 Overall performance • Resolution: δ Q = 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 �ux: high-resolution mode: > 10000 n s-1 high-intensity mode: > 60000 n s-1 4.2 Monochromator • MgLi velocity selector • Wavelength spread ∆λ /λ = 0.2 • Wavelength range λ = 10 - 30 Å (maximal �ux at 12.8 Å) 4.3 Aperture sizes • 1 x 1 mm2 – 5 x 5 mm2 4.4 Beam size at 9.5 m • 0 x 0 mm2 – 100 x 25 mm2 4.5 Beam size at 1.3 m • 0 x 0 mm2 – 15 x 10 mm2 3 http://dx.doi.org/10.17815/jlsrf-1-28 https://creativecommons.org/licenses/by/4.0/ Introduction Typical Applications Sample Environment Technical Data Overall performance Monochromator Aperture sizes Beam size at 9.5 m Beam size at 1.3 m