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| Home > Publications database > Spherical neutron polarimetry at MAGiC |
| Poster (Invited) | FZJ-2025-03163 |
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2025
Abstract: The instrument MAGIC at ESS has been designed with an option for longitudinal XYZ polarisation analysis, highly performing in a wavelength band from 2 to 6 Å. A novel extension to the instrument MAGIC will be spherical neutron polarimetry. To date spherical neutron polarimetry has been routinely established only in zero-field techniques, e.g. Cryopad[1], for measuring the full polarisation tensor for single Bragg peaks on monochromatic instruments. Here we present a more powerful alternative route to spherical polarimetry based on a precession technique [2,3] that can be fully adapted to a pulsed, polychromatic neutron beam and enables us to cover simultaneously a large section of the reciprocal space in time-of-flight Laue diffraction. Implementing spherical polarimetry by precession on the instrument MAGIC requires precise magnetic field design. Two coils in the incoming beam path rotate the polarisation with respect to the field axis, determining inclination and precession angles. Both coils are ramped in time according to the neutrons’ speed. A common phase angle is achieved by an additional, time-independent spin-echo coil. Full simulations of the polarised neutron transport on the instrument MAGIC not only demonstrate the feasibility of spherical polarimetry but also its excellent performance. [1] F. Tasset, Zero field neutron polarimetry. Physica B: Cond. Mat. 156, 627-630 (1989).[2] W. Schweika, Time-of-flight and vector polarization analysis for diffuse neutron scattering. Physica B: Cond. Mat. 335,157 -163 (2003).[3] W. Schweika, S. Easton and K.U. Neumann. Vector Polarization Analysis on DNS. Neutron News, 16(2), 14-17 (2005).
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