Hot neutron four-circle diffractometer
Reactor hall, hot neutron beam H3
Take-off angle 2θM
13 - 56 °
0.25 - 0.85 Å
0.6 x 0.6 cm2
-20 <2θ <120°
-12.5 <ν< 25°
Position sensitive with 32 x 32 pixels
2 x 2 mm2
64 x 64 mm2
Displex cryostat with J-T stage
Peltier cooler gas flow furnace
Closed shell furnace
4-circle He-flow cryostat
The diffractometer D9 is used for precise and accurate measurements of Bragg intensities up to very high momentum transfer. The resolution allows routine recording of extended data sets for the detailed study of atomic disorder and atomic thermal motions.
The wavelength of the neutrons is among the shortest available at any reactor in the world.
The monochromator is a Cu crystal in transmission geometry using the (220) planes.
The instrument is placed on a Tanzboden floor allowing a continuous choice of wave-lengths in the range from 0.35 to 0.85 Å. In order to suppress λ/2 contributions several resonance filters are available (0.48 Å, 0.55 Å, 0.70 Å and 0.84 Å).
In its standard ‘four-circle’ geometry the sample holder is an Eulerian cradle with offset χ-circle. A recent development also allows measurement in ‘normal beam’ (lifting-counter) geometry (i.e. measurement with cryomagnet, orange cryostat, etc.)
A small two-dimensional area detector is available for studies of satellites and twinning. It covers 32 x 32 pixels of (0.25°)2, and programs are available for intensity integration using this system.
Measurement of one Bragg-reflection normally takes a few minutes, and recording of a full set of data a few days. If the crystal is studied as a function of temperature, pressure or other, the total measurement time is about a week.