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The NCNR Spin-Polarized Triple-Axis Spectrometer (SPINS)

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). Incident Energy 14 ~ 2 meV ( 2.4 ~ 6.1 Å )

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The NCNR Spin-Polarized Triple-Axis Spectrometer (SPINS)

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  1. 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

  2. The NCNR Spin-Polarized Triple-Axis Spectrometer (SPINS) • Incident Energy • 14 ~ 2 meV ( 2.4 ~ 6.1 Å ) • Energy Resolution • 0.02 ~ 1 meV • Special Equipments • Supermirror Transmission Polarizer • A stack of single crystal Si plates with Fe/Si supermirror coatings • Multi-crystal Analyzer • 11 Horizontally Focusing PG Blades • Position Sensitive Detector • 3He, 20 × 25 cm2 • Filters • PG or Be filters before sample • Be or BeO filters after sample The SPINS instrument with a super-conducting magnet.

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

  4. Sample D2q Monochromator Single Detector L = distance from sample to HF analyzer wa = total width of HF analyzer D2q = wa sinqa/L ~ 9 degree for Ef=5 meV at SPINS Multicrystal Analyzer The SPINS Operation Modes II:Horizontally Focusing (HF) Analyzer Mode Relaxed Q-resolution Useful for studying systems with short-range correlations

  5. Sample Position-Sensitive Detector D2qi hw Flat Analyzer qai qa Q The SPINS Operation Modes III:Multiplexing Detection System for TAS ~1meV qai = qa + D2qi = qa - atan(x sinqa/(L+xcosqa)) kfi = ta/2sinqai Qi = ki - kfi Probes scattering events at different energy and momentum transfers simultaneously Survey (hw-Q) space by changing the incident energy and scattering angle

  6. PSD Low-pass Filter Sample w Be or BeO L Ei S(Q,w) dw The PSD measures Ei-Ecutoff The SPINS Operation Modes IV:Position-Sensitive Detector in Two-Axis Mode The filter passes only those neutrons with 0 < Ef < Ecutoff Large angular acceptance = w / L ~ 11o for SPINS

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