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Polarized Neutrons in ANSTO From LONGPOL to Pelican, Taipan, Sika, Platypus and Quake Dehong Yu and Shane Kennedy Bragg Institute, ANSTO, Australia Slide 2 LONGPOL (1973-~1980) Location/ beamtube 6HGR9 @ HIFAR, radial tube with =5.9 mm Monochromator Velocity selector with =3.6 & =13 % Polarizer & Analyzer Iron Filters with t =6 mm in H =1 T, P =33 % Spin flipper R-F coil with =0.5 MHz in H =17 mT, =98 % Detector 4 x =2 BF 3 tubes (RSN 44A) in parallel Initial purpose: studies of magnetic diffuse (static) scattering Design criteria: separate magnetic & nuclear components, high intensity, low q resolution Slide 3 LONGPOL Later Development Polarizer Spin flipper Slide 4 LONGPOL Energy Analysis Flipper drive pulse sequence Intensity variation for non-spin-flip scattering Intensity variation for spin-flip scattering Cross-correlation of intensity with drive sequence Direct separation of spin-flip and non-spin flip scattering. TOF energy analysis Modulation of neutron polarization using pseudo-random pulse train to drive spin flipper, Cross-correlation of intensity with the drive sequence Slide 5 LONGPOL - Science Served for more than 30 years Produced important scientific studies including: spin glass nature of Cu 95 Mn 5 short range order in -MnNi flux relaxation in high Tc superconductors crystal field transitions in PrAl 3 magnetic phase of Fe 2 MnSi magnetic domains in amorphous Fe-Zr Slide 6 Lessons from LONGPOL Fix Geometry means non-flexibility Compact design means Difficulty to access Limitation to different sample environment Low flux, long data acquisition time Statistic chopper Relative high background Only works well for strong signals Slide 7 New Instruments in OPAL Wombat (HIPD) Kowari (RS) Echidna (HRPD) Koala (QLD) Platypus (Ref) Quokka (SANS) Taipan (TAS) Sika (CTAS) Pelican (TOFPAS) Slide 8 Pelican - TOFPAS Slide 9 TOF-PAS Preliminary Specifications Design goals: Inelastic & quasi-elastic neutron spectroscopy time focusing TOF spectrometer (Comparable w/- IN6 @ ILL) + Polarization analysis capability (Comparable w/- D7 @ ILL) Preliminary Specs. to reach the design goals Neutron Wavelength: 2.4 6.3 , (14.2 meV 2.1 meV) Energy resolution: 50 eV to 350 eV (~2.5%) Q range: 0.05 -1 - 5 -1 Solid angle: Steradians (non-pol), Steradians (pol) Neutron flux at sample: ~ 8 x10 6 n/cm 2 /s at 3.7 , (full beam) Slide 10 Current Status - Stage 1 Conceptual design finished, Dance floor installed Monochromator stage ordered, Beam Monitor ordered Monochromator shield arrived, Installation started 40 < 2 < 140; 2.1 meV < Ei < 14.2 meV, (HOPG) Slide 11 The TOF-PAS Dance floor The TOF-PAS granite dancefloor (area = 38 m 2 ) -sufficient for 5m flight path from monochromator to detector over all possible take-off angles. 5.4 metre Slide 12 Stage 2 Phase 1 - Conceptual Design General considerations Multiple HOPG monochromator (vertical or double focusing), mosaic about 0.5 o Wavelength filter: Cold Beryllium filter for above 4.1 and a HOPG diffraction filter for < 4.1 . Beam Chopper: Double Stage Fermi Chopper Sample stage: standard A-Z system Collimation system (after sample) Detector: 250 PSD 3 He tube ( = 12.5 mm and length = 1m), cover about Steradian (3.125 m 2 ) Spectrometer Tank: Vacuum or gas filled (He or Ar ?) Energy resolution: E/E i = 2.5% (50eV to 300 eV) Slide 13 Polarization Analysis Polarizer: Supermirror bender Spin Flipper: Mezei flipper; Analyzer: Supermirror bender, and 3 He polarizing filter is also considered if it becomes available in ANSTO. Guide field: to be designed Polarizing benderAnalyzing bender: (8 elements) Slide 14 Polarization Analysis Slide 15 Budget Estimation Stage 2 ItemCost (A$ K) Sub-total Stage 2 Capital4,792 HR789 Running254 Total estimate for stage 2 Contingency (20%) 5,835 1,167 Total7002 Slide 16 Project Schedule Stage 1: Front End Monochromator shield, stage and dance floor Stage 2: Whole Instrument 20052006200720082009 Schedule: Standard components (stage 1) Conceptual design Engineering design Manufacture & procure Assemble & install Commissioning Slide 17 -TAS Incident E: 5 meV 120 meV Energy Transfer: up to 80 meV Scattering angle 2 m : 15 o 85 o Analyzer scattering angle 2 A : -110 o 110 o Double focusing Mono. and Analyzer. Slide 18 TOF-Neutron Reflectometer Horizontal sample Solid solid Liquid solid Polarization option Slide 19 Transmission Polarizer Ref. and SANS iron yoke adsorbing borated glass (Non-magnetic) m=3 supermirrors Permanent magnets 50 mm Elevation looking along the beam (m=3) FeSi polarizing supermirror on both sides of thin Si wafers Elevation perpendicular to the beam 1200 mm = 3 to ~17 RF spin flippers before & after sample Slide 20 Sample environments Cryo-free cryo- furnace 4 K 800 K Arrived One system is commissioned Liq. He cryostat 1.4 K 300 K Arrived 3 He cryostat insert ~300 mK Dilution refrigeration ~30 mK 7.4 Tesla cryo- free cryo-magnet Commissioned in ANSTO 5 Tesla cryo- free cryo- magnet (N.Z. design for Reflectometry/ SANS) Under design HMIs 15 Tesla cryomagnet. Proposed Slide 21 TOFPAS - (Q,) TOF-PAS SikaTaipan Heavy fermions Molecular & lattice vibrations Critical scattering Spin waves Molecular rotations