The NCNR Spin-Polarized Triple-Axis Spectrometer (SPINS) The SPINS instrument is located at the heart of the cold neutron guide hall of the NIST Center for Neutron Research. SPINS

The NCNR Spin-Polarized Triple-Axis Spectrometer (SPINS) The SPINS instrument with a super-conducting magnet. zIncident Energy y14 ~ 2 meV ( 2.4 ~ 6.1 Å ) zEnergy Resolution y0.02 ~ 1 meV zSpecial Equipments ySupermirror Transmission Polarizer  A stack of single crystal Si plates with Fe/Si supermirror coatings yMulti-crystal Analyzer x11 Horizontally Focusing PG Blades yPosition Sensitive Detector  3 He, 20 × 25 cm 2 yFilters xPG or Be filters before sample xBe or BeO filters after sample

The SPINS Operation Modes I: Conventional Triple-Axis Spectroscopy (TAS) TAS is ideally suited for probing small regions of phase space Shortcoming: Low data collection rate A single point at a time Multicrystal analyzer and position-sensitive detector Improvement Monochromator Sample Analyzer Single Detector Neutron Source

The SPINS Operation Modes II: Horizontally Focusing (HF) Analyzer Mode Monochromator Multicrystal Analyzer Sample Single Detector  L = distance from sample to HF analyzer w a = total width of HF analyzer  2  = w a sin  a /L ~ 9 degree for E f =5 meV at SPINS Relaxed Q-resolution Useful for studying systems with short-range correlations

The SPINS Operation Modes III: Multiplexing Detection System for TAS Sample Flat Analyzer Position-Sensitive Detector 2i2i aa aiai  a i =  a +  2  i =  a - atan(x sin  a /(L+xcos  a )) k f i =  a /2sin  a i Q i = k i - k f i Survey (h  -Q) space by changing the incident energy and scattering angle Probes scattering events at different energy and momentum transfers simultaneously hh Q ~1meV

The SPINS Operation Modes IV: Position-Sensitive Detector in Two-Axis Mode The PSD measures E i -E cutoff EiEi S(Q,  ) d  Large angular acceptance = w / L ~ 11 o for SPINS Sample Low-pass Filter PSD L w Be or BeO The filter passes only those neutrons with 0 < E f < E cutoff