Journal of large-scale research facilities, 1, A14 (2015) http://dx.doi.org/10.17815/jlsrf-1-37 Published: 19.08.2015 RESEDA: Resonance spin echo spectrometer Heinz Maier-Leibnitz Zentrum Technische Universität München Instrument Scientists: - Christian Franz, Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, Germany, phone: +49.(0)89.289.14760, email: christian.franz@frm2.tum.de - Thorsten Schröder, Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, Germany, phone: +49.(0)89.289.14760, email: thorsten.schroeder@frm2.tum.de Abstract: RESEDA (resonance spin echo for diverse applications), a high-resolution resonance spin- echo spectrometer, operated by the Technische Universität München, is installed at the cold neutron guide NL5-S in the Neutron Guide Hall West. The instrument gives access to a large time and scattering vector range for quasi-elastic measurements. 1 Introduction RESEDA (see Figure 1 and 2) supports longitudinal neutron resonance spin echo (LNRSE, time range from 0.001 to 20 ns for λ = 8 Å) and modulation of intensity with zero-e�ort (MIEZE, time range from 0.001 to 20 ns for λ = 8 Å) experiments. At RESEDA, the analysis of S(Q,τ ) provides characteristic parameters, e.g. relaxation time and amplitude of the dynamic processes in the sample investigated. The determination of S(Q,τ ) is feasible for di�erent Q-values and/ or di�erent temperatures and pressures. NRSE experiments require non-depolarising sample environment conditions. For MIEZE experiments (and in contrast to NRSE) the spin manipulation and analysis is realised solely before the sample. There- fore, the MIEZE method enables high-resolution study of depolarising samples, under magnetic �eld and/ or within depolarising sample environments. However, as a consequence of the polarisation anal- ysis before the sample, MIEZE experiments are limited to a smaller Q-range than NRSE measurements. Next to 3He detectors, a 2D CASCADE detector with an active area of 20 cm x 20 cm characterised by a spatial resolution of 2.6 mm2 and a time dynamics of the order of a few MHz is available (Häußler et al., 2011; Schmidt et al., 2010). Hence, RESEDA is in addition suited to (polarised) small angle neutron scattering (SANS) applications. 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-1-37 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A14 (2015) http://dx.doi.org/10.17815/jlsrf-1-37 Figure 1: Instrument RESEDA (Copyright by W. Schürmann, TUM). 2 Typical Applications • Quasi-elastic measurements: e.g. to determine the dynamics of water in porous media, polymer melts, di�usion processes in ionic liquids as well as magnetic �uctuations in single crystals, powder samples and thin �lms • (Polarised) Small Angle Neutron Scattering (SANS): e.g. to investigate the di�raction pattern of magnetic structures and vortex lattices to choose suited re�ections for a line-width determination • Spherical polarisation analysis 3 Sample Environment At RESEDA the whole sample environment of the MLZ is applicable. Depolarising conditions are lim- ited to MIEZE experiments. • Available temperature range: 50 mK (dilution insert, see below) up to more than 1300 K (high temperature furnace, non-depolarising) • Maximal pressure: 7 GPa • Maximal magnetic �eld: 7.5 T Available cryostats: • Closed cycle cryostat: (3 K < T < 300 K) • 3He insert: (450 mK < T < 300 K) • Dilution insert: (50 mK < T < 6 K) 4 Technical Data 4.1 Primary beam • Neutron guide: NL5-S • Guide cross section: 29 x 34 mm2 • Wavelength selection: Velocity selector (max. 28000 rpm) • Wavelength range: λ = 3 – 12 Å • Wavelength bandwidth at sample position: ∆λ /λ = 9 – 20 % • Polariser: V-cavity (length: 2 m, coating: m = 3) 2 http://dx.doi.org/10.17815/jlsrf-1-37 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-1-37 Journal of large-scale research facilities, 1, A14 (2015) Figure 2: Schematic drawing of RESEDA. 4.2 Spectrometer • Optional polariser before sample: V-cavity (length: 30 cm, coating: m = 4) • Length of the spectrometer arms: 2.6 m • Two secondary spectrometer arms: SANS (MIEZE) arm and LNRSE arm • For polarisation analysis available: V-cavity, Bender • Detectors: 3He counter or 2D detector (CASCADE) 4.3 Characteristic parameters • Flux at sample position: ϕ ≥ 106 n cm-2 s-1 (at λ = 5.3 Å) • Frequency range of RF coils: 35 kHz – 1.7 MHz • Maximum scattering angle: 2θ = 93° • Maximum scattering vector: Q = 2.5 Å-1 (at λ = 3 Å) • Spin echo time range: τ = 0.001 – 20 ns for λ = 8 Å • Energy resolution: 0.03 µeV – 0.1 meV References Häußler, W., Böni, P., Klein, M., Schmidt, C. J., Schmidt, U., Groitl, F., & Kindervater, J. (2011). Detection of high frequency intensity oscillations at RESEDA using the CASCADE detector. Review of Scienti�c Instruments, 82(4), 045101. http://dx.doi.org/10.1063/1.3571300 Schmidt, C. J., Groitl, F., Klein, M., Schmidt, U., & Häussler, W. (2010). CASCADE with NRSE: Fast Inten- sity Modulation Techniques used in Quasielastic Neutron Scattering. Journal of Physics: Conference Series, 251(1), 012067. http://dx.doi.org/10.1088/1742-6596/251/1/012067 3 http://dx.doi.org/10.17815/jlsrf-1-37 http://dx.doi.org/10.1063/1.3571300 http://dx.doi.org/10.1088/1742-6596/251/1/012067 https://creativecommons.org/licenses/by/4.0/ Introduction Typical Applications Sample Environment Technical Data Primary beam Spectrometer Characteristic parameters