RESEDA-The new resonance spin echo spectrometer using cold neutrons at the FRM-II

We have built a neutron resonance spin echo (NRSE) spectrometer with two secondary spectrometer arms, in order to double the solid angle of detectable neutrons. NRSE is well adapted for building up a multi-detector spectrometer, because it needs only compact magnetic coils. Compared to neutron spin echo (NSE), stray fields are much less important and can be suppressed completely by means of mumetal shielding. The second arms of the spectrometer are designed identically and allow for measuring at two different q-values simultaneously. By varying the radio frequency (RF) in the range 30-780 kHz, spin echo times up to 10 ns are achievable. Small spin echo times down to 1 ps are realized by means of additional NSE coils within the zero field regions. The instrumental resolution has been determined using a standard elastic scattering sample, and the function of the spectrometer is demonstrated by measuring diffusive dynamics in a protein solution.