Combining neutron spin-echo (NSE) and three axis spectrometries (TAS) can enhance the energy resolution of three-axis spectrometers to the µeV range - typically two orders of magnitude better than for TAS alone. However, within the standard NSE configuration, lifetime measurements of dispersing modes are barely doable, owing to the impossibility to tilt the coil surface. As shown by Golub and Gaehler (1987), this difficulty can be counter passed by using a sequence of rotating resonance π-flippers, the neutron-resonance spin-echo technique (NRSE).

ZETA (Zero Field Spin Echo) is a removable device for NSRE. It can be installed on some of the TAS instruments at the ILL. The first version of ZETA was demonstrated on IN3 while a new version is now operational on IN22.