Pulsed LINAC Neutron Diffraction

Abstract

WE have successfully tested a new method of obtaining neutron diffraction patterns from polycrystalline specimens using a pulsed linear accelerator (LINAC) as a neutron source in conjunction with a time-of-flight (TOF) detection system. The TOF technique for neutron diffraction has been used by various investigators since the pioneering studies by Buras et al.^1–4, and its advantages for studies at high pressure have been demonstrated recently by Brugger et al.^5,6. All the previous applications of the TOF technique to neutron diffraction have used a reactor as a neutron source, and generally the pulsing of neutrons has been achieved by means of a fast chopper. In our application, however, the normal pulsed operation of the accelerator eliminates the need for an elaborate and expensive chopper. Furthermore, it has been found that the flux of usable neutrons provided by an accelerator such as the Rensselaer LINAC (Troy, New York) is quite high, as judged by the satisfactory diffraction pattern for an NiO specimen (Fig. 1) obtained in only 4 h in less than optimum conditions (the main features of the pattern could be discerned in the first 2 min of operation). Accelerator neutron sources⁷ have been used for a variety of other purposes, but there has been no report of their application to neutron diffraction studies of polycrystalline substances.