Journal of large-scale research facilities, 1, A12 (2015) http://dx.doi.org/10.17815/jlsrf-1-35 Published: 19.08.2015 PANDA: Cold three axes spectrometer Heinz Maier-Leibnitz Zentrum Forschungszentrum Jülich, Jülich Centre for Neutron Science Instrument Scientists: - Astrid Schneidewind, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany, phone: +49(0) 89 289 14749, email: a.schneidewind@fz-juelich.de - Petr Čermák, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany, phone: +49(0) 89 289 11773, email: p.cermak@fz-juelich.de Abstract: The cold three axes spectrometer PANDA, operated by JCNS, Forschungszentrum Jülich, o�ers high neutron �ux over a large dynamic range keeping the instrumental background comparably low. 1 Introduction PANDA is situated on the cold neutron beam-tube SR-2 in the Experimental Hall. The high �ux is achieved by neutron guide elements in the beam tube, a short source-to-monochromator distance, and the double-focussing monochromator and analyzer crystals. Options for high energy and high q-resolution are available. With dedicated sample environments for strong magnetic �elds and very low temperatures, PANDA is ideally suited for the studies of magnetism and superconductivity on single crystals. Lattice dynamics and magnetic structures are investigated successfully, too. A polarised neutron set-up using both Heusler monochromator and analyzer as well as a sample-space Helmholtz-coil set for longitudinal polarisation analysis is available. 2 Typical Applications Magnetic properties • Spin-waves • Crystal �eld excitations • Excitations in low dimensional systems • Magnetic vs nuclear scattering 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-1-35 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A12 (2015) http://dx.doi.org/10.17815/jlsrf-1-35 Figure 1: Instrument PANDA (Copyright by W. Schürmann, TUM). Lattice dynamics • Phonon dispersion • Field dependent phonons General • Critical scattering at phase transitions • Magnon - phonon interaction • Soft mode • Central peak • Di�raction with analyser: dE close to 0 high E & Q resolution extremely low background 3 Sample Environment The sample table of PANDA allows for a variety of sample environments, and may easily be adapted to user speci�c devices. Among other, PANDA disposes routinely operated sample environment for: Low temperature: • Closed cycle cryostat (3 K < T < 300 K) • Variox cryostat (1.6 K < T < 100 K) • 3He insert (0.5 K < T < 300 K) • Dilution insert (50 mK < T < 1 K) Vertical magnetic �eld: • Cryomagnet V5T Hmax = 5 T (1.5 K < T < 100 K) • Closed-cycle magnet V7.5T Hmax = 7.5 T �eld at low and high temperatures available 3He and dilution inserts available 2 http://dx.doi.org/10.17815/jlsrf-1-35 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-1-35 Journal of large-scale research facilities, 1, A12 (2015) Figure 2: Schematic drawing of PANDA. High temperature: • High temperature furnace 300 K < T < 2100 K sample space: Ø 50 mm, h = 50 mm Typical dimensions for sample space: • Ø 50 mm, h = 70 mm, for details contact instrument scientists 4 Technical Data 4.1 Monochromators • PG(002) (d = 3.355 Å) 20° < 2ΘM < 132° 1.05 Å-1 < ki < 4.0 Å-1 variable horizontal and vertical focussing • Heusler (d = 3.35 Å, polarised neutrons) 20° < 2ΘM < 120° 1.1 Å-1 < ki < 4.0 Å-1 variable vertical focussing 4.2 Analysers • PG(002) -130° < 2ΘA < 100° 1.05 Å-1 < kf variable horizontal focussing • Heusler (polarised neutrons) -130° < 2ΘA <100° 1.05 Å-1 < kf variable horizontal focussing 3 http://dx.doi.org/10.17815/jlsrf-1-35 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A12 (2015) http://dx.doi.org/10.17815/jlsrf-1-35 4.3 Detectors • 1” 3He tube (focussing mode) • 2” 3He tube (collimated mode) 4.4 Flux at sample PG monochromator vertically focussed, horizontal �at, no collimation: • 1.9 · 107 n cm-2 s-1 for ki = 1.55 Å-1 Be Filter • 5.5 · 107 n cm-2 s-1 for ki = 2.662 Å-1 PG Filter 4.5 Main parameters • Scattering angle at the sample: 5° < 2ΘS < 125° (moveable beam-stop) • Energy transfer up to 20 meV • Momentum transfers up to Q = 6 Å-1 (depending on ki) 4.6 Filters for higher order suppression: • PG (l = 60 mm); kf = 2.57 Å-1 or 2.662 Å-1 • Be (closed-cycle cryostat, T ≤ 45 K); kf = 1.55 Å-1 • BeO (liq.-N2 cooled); kf = 1.33 Å-1 4 http://dx.doi.org/10.17815/jlsrf-1-35 https://creativecommons.org/licenses/by/4.0/ Introduction Typical Applications Sample Environment Technical Data Monochromators Analysers Detectors Flux at sample Main parameters Filters for higher order suppression: