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NMI3 JRA-PNT FIRST TEST OF MUPAD ON TAS IN22

NMI3 JRA-PNT FIRST TEST OF MUPAD ON TAS IN22. MUPAD on IN22 Measurements on MnSi Comparison with CRYOPAD Perspectives. Contributors to the realization of the project: TUM : M. Janoschek, A. Emmert, P. Böni ILL: S. Klimko, R. Gähler

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NMI3 JRA-PNT FIRST TEST OF MUPAD ON TAS IN22

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  1. NMI3 JRA-PNT FIRST TEST OF MUPAD ON TAS IN22 • MUPAD on IN22 • Measurements on MnSi • Comparison with CRYOPAD • Perspectives Contributors to the realization of the project: TUM : M. Janoschek, A. Emmert, P. Böni ILL: S. Klimko, R. Gähler CEA-Grenoble : L.P. Regnault, C. Boullier, B. Geffray, F. Mantegezza, B. Longuet NMI3 JRA-PNT LLB/Saclay 18-19/11/2004

  2. NMI3 JRA-PNT MUPAD ON IN22

  3. NMI3 JRA-PNT MUPAD ON IN22 Coupling and precession coils (ki-arm) n

  4. NMI3 JRA-PNT MUPAD on IN22 (June-July 2004) CRYOPAD MUPAD

  5. NMI3 JRA-PNT MUPAD : CALIBRATION In the direct beam and on a 25x17x2 mm3 graphite (PG) sample • Mechanical adjustement • Optimization of currents in the coupling coils • Optimization of the m-metal shielding (slits) • Tuning of correction coils (guide fields) • Determination of field integrals (precession coils) in the direct beam` Success: Principles work (coils, shielding,…) • Hsample< 0.5 mG over 30 cm • Harm~ 3 mG over 18 cm Problems: - m-metal continuity - Stray field of guide-fields Calibration of the di precession coil

  6. NMI3 JRA-PNT SNP on MnSi with MUPAD • Itinerant “weak” ferromagnet (Tc≈29 K) • Single spiral structure due to DM interactions (m≈0.4mB) • Chiral contribution to Pxy and Pyx(Maleyev 1962; Blume 1963) k1≈(0.017, 0.017, 0.017) k4≈(0.017, -0.017, -0.017) SNP on nuclear and magnetic Bragg peaks: [2 0 0], [1 1 1], [0 1 1], [0 1 1]± and [1 1 1] ± Test on magnetic excitations:

  7. NMI3 JRA-PNT SNP on MnSi Polarization matrix on nuclear Bragg peaks Angular accuracy: ≈1° to 5° depending on Pij (NB: calibration on a PG sample)

  8. NMI3 JRA-PNT SNP ON MnSi WITH MUPAD [0 1 1]± [0 1 1]± q=(Qh, 0.983, 0.983) q=(1-Qh, Qh, Qh) Scan “xx” (P0 // Q) (symmetric/non-chiral) Scan “yx” (difference I+-I-) (antisymmetric/chiral) NB: The chiral term can be obtained from longitudinal polarimetry (xx and -xx)!!

  9. NMI3 JRA-PNT TEST ON MnSi Inelastic scattering (kf≈2.662Å-1; DE≈3 meV) Q=(qa, 0.983, 0.983) Inelastic “spurion” qa=0.19 Magnetic excitation qa=0.15 MUPAD works better on broad signals (idem CRYOPAD)! (averaging effect of various aberrations)

  10. NMI3 JRA-PNT PERSPECTIVES • Present accuracy about 5 times worth than CRYOPAD • Sensitivity to outer magnetic fields (cryomagnet on neighboring spectro) • Possible improvements: - Double m-metal shielding for the arms - Better continuity between arm and sample shielding - Optimization of guide fields (reduction of stray fields) - Motorized/encoded coupling coils (calibration procedure)

  11. NMI3 JRA-PNT MUPAD: PRINCIPLE MUPAD : MU-metal Polarization Analysis Device (§ R. Gähler) • Mu-metal based • Zero-field chamber • No cryogenics • Flat precession coils • Compact device • Simple to tune (?) • Low cost

  12. NMI3 JRA-PNT MUPAD ON IN22 Coupling and precession coils

  13. NMI3 POLARIZED NEUTRON RECHNIQUES Task 3:Developments of the NRSE technique for an increase in the resolution of inelastic scattering instruments • Development of RF flipper coils for Ei ≈ 60-70 meV ILL (P7), CEA-Grenoble (P3), MPI Stuttgart (O6) and RIKEN/Japan (O9) - Construction of a user-oriented "high-energy" zero-field spin echo option for IN20 (ILL) and IN22 (CRG) ("ZETA-plus") • CEA-Grenoble (P3) Contributors to the project: CEA-Grenoble: L.P. Regnault, C. Boullier,B. Geffray, F. Mantegezza, B. Longuet ILL: S. Klimko, R. Gähler NMI3 JRA-PNT LLB/Saclay 18-19/11/2004

  14. m-metal slits

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