RESEDA

This instrument is focussed on cold neutrons. All parameters given here are valid during the current operation of FRM II. Please get in touch with the instrument team well in advance for all further details (length of experiment etc.).

Instrumentscheme RESEDA

The neutron spin echo spectrometer RESEDA (Resonance Spin Echo for Diverse Applications) is dedicated to the exploration of slow dynamics and fluctuations in hard and soft condensed matter systems. RESEDA is located at the end position of NL5-S in the Neutron Guide Hall West. Following a major revision and upgrade, RESEDA now permits longitudinal NRSE (LNRSE) spectroscopy as well as longitudinal MIEZE (Modulation of Intensity with zero effort) operation with sub-µeV energy resolution and an unprecedented dynamic range. When operated as a MIEZE spectrometer, data may be recorded readily in depolarizing sample environments, such as very large magnetic fields. Likewise, depolarizing substances, such as ferromagnets or superconductors, strong incoherent scattering materials containing, for instance, hydrogen may be studied.

RESEDA’s LNRSE option represents a set-up akin a conventional NSE spectrometer. Conventional NSE coils between the resonant flipper coils may be used for field integral subtraction, thereby massively extending the dynamic range. Typical momentum transfers currently accessible are between 0.035 Å^-1 and 1 Å^-1. Remarkably, even for the highest resolutions reached so far, exceeding 50 ns, no correction coils are required.

A unique feature of RESEDA is the MIEZE set-up for studies under depolarizing conditions. MIEZE also proves to be extremely successful in combination with SANS (MIEZE-SANS) where scientific challenges in ferromagnets, superconducting vortex lattices, and magnetic skyrmion systems have been addressed recently. The implementation of phase-locking of the neutron polarisation enables inelastic measurements as demonstrated for magnons in ferromagnetic iron, where the intermediate scattering function features an oscillatory component. The standard range of scattering vectors ranges here from 0.005 Å^-1 to 1.7 Å^-1 at spin echo times from 0.03 ps up to 2.5 ns. For neutron detection the MIEZE option uses a bespoke Cascade 2D position sensitive detector with an active area of 200 × 200 mm². An application to calculate the signal reduction factor for various sample geometries can be found here.