Thermal neutron diffractometer for single-crystal and fibre diffraction D19
The white beam (polychromatic) from the thermal tube H11 arrives at the monochromator.
Monochromatic diffracted beams reache the sample – a single crystal - located at the centre of the Eulerian cradle.
The curved two-dimensional position-sensitive detector (PSD) records all diffracted beams within its angular range (120° × 30°). This dramatically speeds up data collection.
If desired, the three angles of the Eulerian cradle are rotated to set the sample to a specific orientation.
The sample is rotated step by step around the vertical axis while the detector records the intensity profils of the diffracted beams.
When the intensities of a large enough number – typically 1000 to 100000 - of Bragg reflections have been collected, they can be used to compute the crystal structure of the sample i.e. to determine the position and nature of its atoms.