Scientific Reviews: High-Resolution Fourier Diffraction at the IBR-2 Reactor

High-resolution time-of-flight (TOF) diffractometers at short-pulse spallation neutron sources (SPS)—the most well-known example is HRPD at ISIS—have proved themselves to be extremely good for various applications. The resolution, R = Δd/d, close to 0.001 or even a bit better, can be easily obtained if a flight path amounts to 50-100 meters. But at so-called “long pulse sources” (LPS), with the pulse width Δt 0 equal to hundreds of microseconds, the flight path would need to be too long if a 0.001 resolution level is required. In this case, effective shortening of the neutron pulse should be done by employing a counter-rotating pair of fast disc choppers (see, for instance, Ref. [1 Mezei, F. 1995. ICANS-XIII conference. PSI Proceedings. 1995. 95-02, I-400 [Google Scholar]]) or the correlation Fourier technique.