Vibrating phase echo concept for small-angle inelastic neutron scattering

Small-angle inelastic neutron scattering measurements are based on the vibrating phase echo concept. The double neutron diffraction is carried out by two thin vibrating single crystals, for example Si or Ge. The neutron beam diffracted at the monochromator crystal M is modulated with a frequency 2 Ω, where Ω is the circular frequency of the ultrasonic transducer. The second crystal A (analyser) vibrates at a frequency Ω with a phase shift φ. A neutron spectrometer on the basis of two vibrating single crystals is suitable within the scattering angle range 0.5' ≤ θ ≤ 50' and within the range of magnitude of the scattering vector Q = (2 to 500) x 10-3 nm-1. The described equipment covers the Q values of major part of the classical optical spectroscopy as well as Q values of part of the spin echo spectroscopy