Thermal energy 3He spin-echo spectrometer for ultrahigh resolution surface dynamics measurements -: art. no. 053109

We present details of a He-3 spin-echo spectrometer, designed to make possible a wide range of new surface dynamics measurements. The apparatus operates at beam energy of 8 meV, sufficiently high to enable processes such as surface Bragg diffraction and permit inelastic and quasielastic scattering measurements at up to momentum transfers of about 4 A(-1). We describe the requirements for the machine, details of the major components used to fulfil these requirements, and the performance of the overall spectrometer. The machine can access a Fourier time range of 0.01 ps-1 ns, and yields a resolution of 3 mu eV for inelastic spectrum reconstruction, although under favorable circumstances quasielastic broadenings as narrow as 20 neV can be resolved, allowing correspondingly slower processes to be studied. (c) 2005 American Institute of Physics.