The sub-neV resolution NSE spectrometer IN15 at the Institute Laue-Langevin

A new ultra-high-resolution neutron spin-echo spectrometer at the ILL, Gren oble, extends the time range for measurements of the intermediate scatterin g function S(q, t) far beyond what has previously been possible. This new d ynamic range approaching the microsecond opens up the possibility for explo ring dynamic phenomena which have been previously unobservable. The various design ideas for the three operational modes (standard, neutron optical fo cusing, and time of flight) will be presented. The standard and focusing co nfigurations are currently operational. In the normal mode, Fourier times b etween 0.03 and 360 ns and momentum transfers q between 0.01 and 0.6 Angstr om(-1) are accessible. Under focusing conditions, the smallest attainable q is about 0.002 Angstrom(-1), and closes the gap to light scattering. Two e xamples of experiments will be presented: the reptation dynamics in an enta ngled linear polymer melt, and the superparamagnetic fluctuations of magnet ic monodomain nano-particles. (C) 1999 Elsevier Science B.V. All rights res erved.