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Task 2. Further developments in neutron spin echo technique

Task 2. Further developments in neutron spin echo technique. FZJ: new correction elements for an extremely high field integral NSE spectrometer. M.Ohl, M. Monkenbusch. Test of the prototype of CE.

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Task 2. Further developments in neutron spin echo technique

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  1. Task 2. Further developments in neutron spin echo technique FZJ: new correction elements for an extremely high field integral NSE spectrometer. M.Ohl, M. Monkenbusch JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  2. Test of the prototype of CE The further test have been done to proof the long term stability of this prototype:more than 100 cycles have been run to test the correction coil for a reliable operation in a foreseen spin echo instrument at the SNS. The correction coil remains stable over the whole period of operation and the glue between the back plate and the spirals fixed the correct position of the correction coil windings. Successful test of the prototype: • homogeneous temperature over the whole Fresnel coil of about 60°C and at the same time a power consumption of 800 W. The next prototype will be build to finally correct a field integral of 1.5 Tm. We expect the next prototype available for tests in august 2005. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  3. Positioning of correction elements • accuracy required perpendicular to axis: ~0.03mm • accuracy required along axis: ~1-3mm • allowed tilt: < 0.10 • thermal drift: stay below these limits (keep it cool => cooling tests) We received the first hexapod prototype for the exact positioning of the correction elements. Due to some minor problems to build this prototype from nonmagnetic materials, some minor changes have to be performed by the company. The next prototype will be delivered on 06/18/2005. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  4. Forschungszentrum Jülich Task 4:Development of thin film based Larmor precession devices Sub-task B: Developments of thin films with the rotating magnetization and reduced losses in RF field as fast spin turners for compact instrumentation (3-d polarimeter, spin-echo set up).Partners:Forschungszentrum Jülich, Joint Institute of Nuclear Research, Dubna A. Ioffe, FZ Jülich JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  5. Forschungszentrum Jülich Spin propagation through a thin magnetic sheet with rotating magnetic field z • Because of the sheet thickness selection, the neutron spin makes half a turn • Finally spin is again in the sheet‘s plane •  Spin is reflected w.r.t. the direction of magnetic field vector B B s x y JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  6. Forschungszentrum Jülich z t = t1 t = t2 B t = 0 s t = t3  = 2t „The spin clock“ is running twice as quick as „the field clock“ In-plane rotating magnetic field the spin Larmor clock JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  7. Forschungszentrum Jülich  = 2T t = t1 T t = 0  T t = t2 T t = t3 T Two spin turners Spin turner 2 Spin turner 1 z H = 0 x y L T t = t1 t = 0 t = t2  = 2t t = t3 Position of spin depends only on T and doesn’t depend on the arrival time t ! JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  8. Forschungszentrum Jülich Intensity modulations of the incident beam spectrum After analyzer: We achieve high-frequency modulation of the spectrum. Modulation frequency is defined by the product L. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  9. Neutron spin echo setup Forschungszentrum Jülich Spin turner 2 Spin turner 4 x Spin turner 3 Spin turner 1 z z L L+L y y f = 50 kHz, L2 = L1 = 1 m / = 20% NSE signal: Simulations (VITESS) The modulation frequency ~L (effective „field integral“) The operational principle is rather similar to NRSE JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  10. Forschungszentrum Jülich How to realize the rotating magnetic field? Superposition of two sinusoidal time dependent fields: Spin precession angle:  Spin-flip condition: B(G) ·(Å)·d(cm) = 66 Coil: d = 1 cm,  = 4 Å B = 16.5 G Thin film: d = 25 m,  = 4 Å B = 6600 G JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  11. Forschungszentrum Jülich Thin film spin turner • Thin magnetic foil of metallic glassy alloys (commercially available): • low Hc: 50 –100 mG • high Bc: 6 –8 kG • thickness: d = 25-50 m • high frequency susceptibility (500 kHz and higher) • rather homogenous Suits quite good for  = (2 – 4) Å JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  12. Inelastic scattering Forschungszentrum Jülich • a moderate improvement in the energy resolution of inelastic and quasielastic scattering experiments in a wide angular (Q-) range • E/E = 0.1 % or better (factor 10-20 w.r.t. TOF) • Inexpensive and technically affordable solution E= 15 meV (=2.3 Å, / =1.5% ) (A. Ioffe, S. Manoshin, Physica B: 529(2004) 45) JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  13. Quasielastic scattering Forschungszentrum Jülich (A. Ioffe, S. Manoshin, Physica B: 529(2004) 45) JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  14. The majority of the experimental work is being currently carried out in the cooperation with Joint Institute of Nuclear Research, Dubna,using the pulsed neutron source IBR-2.V. Bodnarchuk will report about details of these experiments. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  15. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  16. z Bg s y x Compensation coil Thin magnetic foil Forschungszentrum Jülich Polarized neutron experiment at IBR-2 - Polarized neutron setup at REFLEX-P Py Sample is placed inside the compensation coil: /2 flipper JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  17. Forschungszentrum Jülich Polarized neutron experiment at IBR-2 Sample: thin filmof metallic glassy alloys Co66Si15B14Fe4Ni (Good Fellow). d = 25 m • Depolarization around B = 0 was not observed. • Control experiment with a shim foil: full depolarization This result has been reconfirmed by vector polarization analysis up at FZJ JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  18. B Forschungszentrum Jülich Vector polarization analysis at FZJ (2004)V. Bodnarchuk (JINR), A. Ioffe (FZJ) Samples: different metal glassy alloys (commercial) Instrument: Set up for 3-d polarization analysis LAP-ND at FZJ • Results: • Spin rotation • Depolarization JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  19. Forschungszentrum Jülich Depolarization on scattered magnetic fields Table of experimental results This alloy is a very good candidate ! Absorption within a few percent JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina * This angle is pure rotation on foil magnetization. It obtained as difference between total turn angle and turn angle of empty coil 23.

  20. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  21. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  22. Forschungszentrum Jülich Quasielastic scattering JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  23. SESANS & SERGIS Forschungszentrum Jülich   Flippers are inclined to achieve higher angular sensitivity  = 4 Å The angular resolution is decoupled from incident beam divergence: the angular resolution is 0.002°, when the incident beam divergence is 0.5°. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  24. B H Hc Forschungszentrum Jülich Spin turner Thin magnetic foil of a metallic glass alloy: • low Hc: 50 –100 mG (Low current for field control ) • high Bc: 6 –8 kG ! • thickness: d = 25-50 m • high frequency susceptibility (500 kHz and higher) (patterning technique, Si-MG multilayers (Theo)) • No heating – no cooling is required, rather homogenous Spin-flip condition: Satisfied for e.g.  = 4 Å, d = 25m JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  25. Forschungszentrum Jülich Co69B12Si12Fe4Mo2Ni A depolarization on scattered magnetic fields? This has been a first and short experiment … However, this MG alloy is already a very good candidate ! JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina * This angle is pure rotation on foil magnetization. It obtained as difference between total turn angle and turn angle of empty coil 23.

  26. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

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