Time-Of-Flight Neutron Diffraction- Neutron diffractometer (TOF)

The instrument is installed at a radial thermal neutron beam. The monochromator system consists of a fast double and two single choppers and a straight neutron guide with 2.5X10 cm² cross section at the exit. The double chopper is designed for a maximum speed of 12000 rpm. While in high resolution mode the very short – 10µs – neutron pulse and the 25 m total flight path allows to obtain a diffractogram with an accuracy of 1.5X10^-3Å (at back scattering mode) in a single measurement on polycrystalline materials, in low resolution mode liquid diffraction can be performed at good neutron intensity up to 12.5 Å^-1 scattering vector value. The beam is filtered by a silicon single crystal against fast neutrons. The double disk chopper (Ch1 and Ch2) has two windows: a 1.5° opening for short pulses (10 μs) and a 15° window for long variable pulses (20–200 μs), that can operate in parallel and in counter rotating mode. The latter option is used to produce very short pulses at high speed. Ch3 defines the bandwidth and Ch4 prevents frame overlap. The instrument is equipped with a large surface back-scattering detector bank consisting of 88 pieces of squashed 3He tubes. It covers 20° scattering angle (2θ=145°–165°).