Neutron time-of-flight diffractometer with a linear-position sensitive detector

A method for recording two dimensional neutron diffraction patterns as a function of the scattering angle and the wavelength of the diffracted neutrons is described, and its results have been examined on a pulsed neutron source, the IBR-30 reactor. The position sensitive detector is composed of an SNM-41 (7 atmosphere helium-3) proportional counter in which high resistance nichrome wire is used as the anode. The determination of the coordinates of the neutron event in the detector is performed using two analog-to-digital converters which analyze the amplitudes of the pulses at each end of the anode wire, and with a special device (a dedicated processor) which includes a scheme for division using digital arithmetic. Tests performed on the IBR-30 reactor have shown that two-dimensional neutron diffraction data shorten the duration of the experiment (by about 20 times) and improve the quaity of the diffraction patterns.