Flat-Cone Diffractometer


Instrument description

A 3-dimensional part of the reciprocal space can be scanned in less then five steps by combining the “off-plane Bragg-scattering” and the flat-cone layer concept while using a new computer-controlled tilting axis of the detector bank. Parasitic scattering from cryostat or furnace walls is reduced by an oscillating "radial" collimator. The datasets and all connected information is stored in one independent NeXus file format for each measurement and can be easily archived. The software package TVneXus deals with the raw data sets, the transformed physical spaces and the usual data analysis tools (e.g. MatLab). TVneXus can convert to various data sets e.g. into powder diffractograms, linear detector projections, rotation crystal pictures or the 2D/3D reciprocal space.

For single crystal work the multi detector bank (four 2D detectors 300x300 mm2) and the sample table can be tilted around an axis perpendicular to the monochromatic beam to investigate upper layers in reciprocal space (Flat-Cone technique). For powder studies, the multi detector bank set on only two positions for a measure the a powder diffractogram of 80° or every detector can be set on an individual position (with gaps between the detectors) for in-situ measurements.


  • complicated distributions of Bragg and superstructure reflections in three dimensions of reciprocal space (Flat-Cone)
  • low intensity sublattice scattering patterns
  • diffuse scattering arising from structural and magnetic disorder
  • magnetic and crystal structures
  • in-situ kinetic of phase transitions and chemical reactions

Selected examples

  • Dirac Strings and Magnetic Monopoles in the Spin Ice Dy2Ti2O7, Morris et al., Science 326 (5951): 411-414 (2009) (link)
  • Patterning of sodium ions and the control of electrons in sodium cobaltate, M.Roger et al., Nature 445, 631-634 (8 February 2007) (link)
  • Magnetic phase control by an electric field, Th. Lottermoser et al., Nature 430, 541-544 (29 July 2004) (link)
  • Electronic Structure and Nesting-Driven Enhancement of the RKKY Interaction at the Magnetic Ordering Propagation Vector in Gd2PdSi3 and Tb2PdSi3, D. Isonov et al., Phys. Rev. Lett. 102, 046401 (2009) (link)
  • Magnetic interaction parameters from paramagnetic diffuse neutron scattering in MnO, D. Hohlwein et al., Phys. Rev. B 68, 140408(R) (2003) (link)

Instrument Data
Beam tube R 1B
Collimation 15', 30', 60' (open)
Monochromator • Cu (220)
• Ge (311)
• PG (002)
Take off angle of monochromator
Wave length • λ=0.091 nm [Cu (200)]
• λ=0.121 nm [Ge (311)]
• λ=0.241 nm [PG (002)]
Flux 2·106 n/cm2s
(flat PG monochromator without collimation)
Range of scattering angles -10°< 2 Θ< 105°
Angle resolution • horizontal resolution: 0.2° - 1.0°
• vertical resolution: 0.5° - 1.0°
• pixel size 0.1°x0.1°
Range of lattice spacing
d resolution
Sample size
Detector four 2D delay-line detectors (PSD 300 x 300 mm2)
Polarized neutrons no
Instrument options • single crystal mode
• powder diffraction mode
Sample environment
Software TVneXus
Tilting angle 0°< μ < 18°

Additional information

Link: Further detail information