Journal of large-scale research facilities, 1, A38 (2015) http://dx.doi.org/10.17815/jlsrf-1-30 Published: 21.12.2015 NREX: Neutron re�ectometer with X-ray option Max-Planck-Institut für Festkörperforschung Heinz Maier-Leibnitz Zentrum Instrument Scientists: - Yury Khaydukov, Max-Planck-Institute for Solid State Research, Stuttgart, Germany at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, phone: +49(0) 89 289 14769, email: y.khaydukov@fkf.mpg.de - Olaf Soltwedel, Max-Planck-Institute for Solid State Research, Stuttgart, Germany at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, phone: +49(0) 89 289 14769, email: o.soltwedel@fkf.mpg.de - Thomas Keller, Max-Planck-Institute for Solid State Research, Stuttgart, Germany at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, phone: +49(0) 89 289 12164, email: t.keller@fkf.mpg.de Abstract: The high resolution neutron/ X-ray contrast re�ectometer NREX, operated by the Max Planck Institute for Solid State Research, is designed for the determination of structural and magnetic properties of surfaces, interfaces, and thin �lm systems. 1 Introduction The instrument is an angle-dispersive �xed-wavelength machine with a default wavelength of 4.28 Å. A horizontal focussing monochromator gives the possibility to switch between modes “high intensity/ relaxed resolution” and “high resolution/ reduced intensity” and provides a beam especially for small samples (down to 5 x 5 mm2 and below). A Beryllium �lter attenuates higher order re�ections. Trans- mittance supermirrors m = 3.5 with a polarising e�ciency of P = 99 % and high e�ciency gradient RF �eld spin �ippers are used for a full 4 spin channel polarisation analysis. The sample is aligned horizontally. By tilting the sample the incident angle is varied. The detector arm can move for GISANS horizontally as well as vertically for specular and di�use scattering mea- surements. Neutrons are detected with a 20 x 20 cm2 position sensitive or a pencil detector. An X-ray re�ectometer can be mounted on the sample table orthogonal to the neutron beam. It allows for the in-situ characterisation of sensitive soft matter samples and neutron/ X-ray contrast variation experi- 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-1-30 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A38 (2015) http://dx.doi.org/10.17815/jlsrf-1-30 ments. Figure 1: Instrument NREX (Copyright by W. Schürmann, TUM). 2 Typical Applications The instrument provides specular and o�-specular re�ectometry as well as grazing incidence small angle di�raction both in polarised and non-polarised modes. While the specular re�ectivity allows determining the scattering length density pro�les (20 – 1500 Å) with nm precession along the surface normal, the o� specular re�ectivity is sensitive to in-plane-inhomogeneity like roughness, (magnetic) domains, vortices in superconductors- and clusters- in the µm-range. To probe lateral (in-plane) struc- tures in the order of atom distance (down to few Å) at the surface, grazing incidence di�raction is provided. 3 Sample Environment A closed cycle crystat (down to 3.5 K) and an electromagnet for �elds up to 0.5 T applicable in all three space-directions with restrictions in �eld strength are provided. Additionally the standard sample environment (magnets up to 7.5 T and 3He inserts for the cryostat down to 50 mK) are available. To the instrument pool belong a cell for investigations at the solid/ liquid interface and a gastight chamber for experiments under de�ned environmental conditions (arbitrary atmospheres: for example de�ned relative humidity) at the solid/ air interface. 4 Technical Data 4.1 Monochromator • Type 7 x 5 HOPG crystals Horizontal focussing • Wavelength: 4.28 Å • Wavelength resolution: 1. . . 2 % 2 http://dx.doi.org/10.17815/jlsrf-1-30 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-1-30 Journal of large-scale research facilities, 1, A38 (2015) • Distance to sample: 2500 mm • Higher order �lter: cooled Be Figure 2: Schematic drawing of NREX. 4.2 Collimation • Vertical Slit sizes: 0.2 – 6 mm Divergence: 0.05 – 1.4 mrad • Horizontal Slit: 0.2 – 100 mm 4.3 Polarisation • Beam polarisation > 99 % • Flipper e�ciency > 99 % 4.4 Detector • 2 pencil detectors 3He • 2D area detector 3He wire chamber • Active area 200 x 200 mm2 • Lateral resolution 3 mm • Distance to sample 2465 mm 4.5 Dynamical- and Q-Range • Specular re�ectivity: 1 : 1 x 10-6 (@ 5 x 5 mm2 sample and full polarisation) • Qz: 0.005 - 0. 5 Å-1 • δ Qz (0 < Qz < 0.2 Å-1) < 0.002 Å-1 3 http://dx.doi.org/10.17815/jlsrf-1-30 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A38 (2015) http://dx.doi.org/10.17815/jlsrf-1-30 4.6 X-rays • Source: Cu-Kα �xed anode (1.54 Å) • Monochromator: Goebel Mirror & Double Ge-Crystal • Detector: 0-dimensional NaI scintillation counter 4 http://dx.doi.org/10.17815/jlsrf-1-30 https://creativecommons.org/licenses/by/4.0/ Introduction Typical Applications Sample Environment Technical Data Monochromator Collimation Polarisation Detector Dynamical- and Q-Range X-rays