D4, a two-axis diffractometer, uses short-wavelength neutrons from the hot source, and measures diffraction patterns over a large Q-range. This feature allows characterisation of local atomic order of non-crystalline materials (glasses, liquids, amorphous solids and solutions) with excellent accuracy.

• Short and intermediate range order in liquids and amorphous materials
• Solving environment of atoms combining isotopic substitution and methods of first and second difference
• Magnetic structure studies on very absorbent systems, such as those containing Gd, Eu, etc.
• Pair-Distribution Function (PDF) analysis of powder diffraction patterns.

The complete scattering range is covered by a large array of microstrip detectors, making the machine very efficient and very stable for difference measurements on small samples. This is crucial feature when the isotopic replacement is used to enhance contrast of particular atomic species. D4 shares the beam tube (H8) with the three-axis spectrometer IN1 and is. therefore, only available for about 50% of the time.