A technique used in X-ray diffraction in which a crystal in powder form is fixed to a thin fibre or thin silica tube, which is then rotated in the path of a beam of monochromatic X-rays. A circular diffraction ring, called the Debye–Scherrer ring, concentric with the undeflected beam is formed. The diffraction pattern is recorded on a cylindrical film, which has its axis parallel to the axis of rotation of the material. The Debye–Scherrer method is used to obtain information about the material. The grains of the powdered crystal must be much larger than the atomic dimensions in order for them to diffract X-rays. The method was devised by Peter Debye and Paul Scherrer (1890–1969) in 1916 and independently by Albert Hull (1880–1966) in 1917.