1. Polarized Neutrons in ANSTO – From LONGPOL to Pelican, Taipan, Sika, Platypus and Quake Dehong Yu and Shane Kennedy Bragg Institute, ANSTO, Australia

2. LONGPOL (1973-~1980) Location/ beamtube 6HGR9 @ HIFAR, radial tube with  =5.9 mm Monochromator Velocity selector with =3.6 Å &  =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

3. LONGPOL – Later Development Polarizer Spin flipper

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

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

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

7. New Instruments in OPAL Wombat (HIPD) Kowari (RS) Echidna (HRPD) Koala (QLD) Platypus (Ref) Quokka (SANS) Taipan (TAS) Sika (CTAS) Pelican (TOFPAS)

8. Pelican - TOFPAS

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 Å – 6.3 Å, (14.2 meV – 2.1 meV) Energy resolution: 50 µeV to 350 µ eV (~2.5%) Q range: 0.05 Å -1 - 5 Å -1 Solid angle: ¾ Steradians (non-pol), ¼ Steradians (pol) Neutron flux at sample: ~ 8 x10 6 n/cm 2 /s at 3.7 Å, (full beam)

10. Current Status - Stage 1 Conceptual design finished, Dance floor installed Monochromator stage ordered, Beam Monitor ordered Monochromator shield arrived, Installation started 40° < 2Θ < 140°; 2.1 meV < Ei < 14.2 meV, (HOPG)

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

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 λ above 4.1 Å and a HOPG diffraction filter for λ < 4.1 Å. Beam Chopper: Double Stage Fermi Chopper Sample stage: standard A-Z system Collimation system (after sample) Detector: 250 PSD 3 He tube (Φ = 12.5 mm and length = 1m), cover about ¾ Steradian (3.125 m 2 ) Spectrometer Tank: Vacuum or gas filled (He or Ar ?) Energy resolution:  E/E i = 2.5% (50µeV to 300 µeV)

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)

14. Polarization Analysis

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

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

17. -TAS Incident E: 5 meV – 120 meV Energy Transfer: up to 80 meV Scattering angle 2Ө m : 15 o – 85 o Analyzer scattering angle 2Ө A : -110 o – 110 o Double focusing Mono. and Analyzer.

18. TOF-Neutron Reflectometer Horizontal sample Solid –solid Liquid – solid Polarization option

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 Å RF spin flippers before & after sample

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 HMI’s 15 Tesla cryomagnet. Proposed

21. TOFPAS - (Q,ω) TOF-PAS SikaTaipan Heavy fermions Molecular & lattice vibrations Critical scattering Spin waves Molecular rotations