Let technical information

Technical specifications relating to LET

Technical Summary

Primary Spectrometer
ModeratorCoupled cold (18K H2)
Choppers2 double disc choppers (6,000-20,000rpm)
1 frame overlap chopper
1 Background suppression chopper
Incident Energies0.5 – 30meV (12 – 1.65 Å)
Incident flight path25m (m=3 converging guide)


Maximum energy resolution5µeV at Ei = 1meV
260µeV at Ei = 20meV
Maximum energy loss80% of incident energy
Minimum momentum transferQmin = 0.032x√Ei
Maximum momentum transferQmax = 1.32x√Ei
Beam size40 x 50mm
Flux at 5meV and 2% resolution5 x 104n cm-1s-1


Secondary Spectrometer
Detector typePosition sensitive 3He counters
Sample to detector3.5m
Horizontal angular range--40o to +140o  
Vertical angular range± 30o
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