MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich
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MLZ (eng)

Lichtenbergstr.1
85748 Garching

PANDA

Cold three-axes spectrometer

PANDA scheme PANDA scheme

The cold three axes spectrometer PANDA offers high neutron flux over a large dynamic range keeping the instrumental background comparably low. PANDA is situated on the cold neutron beam-tube SR-2 in the Experimental Hall. The high flux 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 very strong magnetic fields 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.

Typical Applications

Magnetic properties

  • Spin-waves
  • Crystal field excitations
  • Excitations in low dimensional systems
  • Magnetic vs nuclear scattering

Lattice dynamics

  • Phonon dispersion
  • Anharmonic effects
  • Polarisations vectors

General

  • Critical scattering at phase transitions
  • Magnon – phonon interaction
  • Soft mode
  • Central peak
  • Diffraction:
    • without analyser: integral E method
    • with analyser: dE close to 0, high E & Q resolution

Sample Environment

The sample table of PANDA allows for a variety of sample environments, and may easily be adapted to user specific devices. Among other, PANDA disposes routinely operated sample environment for:

Low temperature

Closed cycle cryostat(3 K < T < 300 K)
Variox cryostat(1.5 K < T < 100 K)
3He insert(0.4 K < T < 300 K)
Dilution insert(50 mK < T < 6 K)
  • typical dimensions for sample space: Ø 50 mm, h = 70 mm

Vertical magnetic field

  • Cryomagnet V15T with optional 3He-4He-dilution insert; Hmax = 13.5 T (50 mK) 1.5 K < T < 100 K
    • max. sample diameter: (12 mm) 19 mm
    • split of coils 20 mm
  • Closed-cycle magnet V7.5T
    • Hmax = 7.5 T
    • field at low and high temperatures available

High temperature

  • High temperature furnace
    • 300 K < T < 2100 K
    • sample space: Ø 50 mm, h = 50 mm

Technical Data

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
  • Si(111) (d = 3.135 Å)
    • 20° < 2ΘM < 132°
    • variable horizontal and fixed vertical focussing
    • 1.15 Å-1 < ki < 4.0 Å-1

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

Detectors

  • 1” ³He tube (focussing mode)
  • 2” ³He tube (collimated mode))

Flux at sample
Monochromator vertically focussed, horizontal flat, 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

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)

Filters for higher order suppression

  • PG (l = 60 mm); kf = 2.57 Å-1 or 2.662 Å-1
  • Be (closed-cycle cryostat, T ≤ 25 K); kf = 1.55 Å-1
  • BeO (liq.-N2 cooled); kf = 1.33 Å-1

Instrument Scientist

Dr. Astrid Schneidewind
Phone: +49.(0)89.289.14749
E-Mail:

Dr. Petr Čermák
Phone: +49.(0)89.289.11773
E-Mail:

PANDA
Phone: +49.(0)89.289.14869/.14813

Operated by

JCNS

Gallery

PANDA
PANDA

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich