High-q-resolution neutron scattering technique using triple-axis spectrometers

A new technique is presented that gives a substantial increase in the wavevector q resolution of triple-axis spectrometers by matching the measurement wavevector q to the reflection (tau)a of a perfect-crystal analyzer. A relative Bragg width of (delta)q/Q  ~  10^(-4) can be achieved with reasonable collimation settings. This technique is very useful in measuring small structural changes and line broadenings that cannot be accurately measured with conventional set-ups, while keeping all the strengths of a triple-axis spectrometer.