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| Hauptseite > Publikationsdatenbank > Spherical neutron polarimetry at MAGiC |
| Hauptseite > Publikationsdatenbank > Spherical neutron polarimetry at MAGiC |
| Poster (Invited) | FZJ-2024-06882 |
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2024
Abstract: Spherical neutron polarimetry has been routinely established using Cryopad [1], measuring in zerofieldthe full polarization tensor for single Bragg peaks. This is a precise tool perfectly suited formonochromatic instruments at reactor sources. How to achieve this goal at ESS and at pulsed sourcesin general with polychromatic beams?There are two feasible solutions. Since such experiments are essentially not limited by flux, a straightforwardsolution for pulsed sources would be to use the Cryopad as a sample environment at instrumentsthat are already equipped for longitudinal polarization analysis.Here we consider an alternative approach based on a precession technique [2,3] that can be fullyadapted to a pulsed, polychromatic neutron beam to cover a large section of the reciprocal space intime-of-flight Laue diffraction. Since this method accepts the non-precessing component for polarizationanalysis, it applies as well to inelastic scattering. In order to make use of the full wavelengthband, the π/2-flipper, which initiates the precession mode, needs to be ramped in time accordingto the neutron’s wavelength and its time-of-flight. A common phase of the precession angle at thesample is not a necessary requirement but can be favorably achieved by an additional spin-echosetup. For an instrument like MAGiC at ESS, spherical polarization analysis can be a straightforwardextension of the existing setup for longitudinal polarization analysis. We are considering thispotential upgrade for the MAGiC instrument and present a relatively simple scheme how to modifythe magnetic field setup for the incoming beam to enable spherical polarimetry. Full simulationsof the polarized neutron transport not only demonstrate the feasibility of spherical polarimetry butalso its excellent performance.[1] Tasset, F. (1989). “Zero field neutron polarimetry”. Physica B: Condensed Matter, 156, 627-630.[2] Schweika, W. (2003). “Time-of-flight and vector polarization analysis for diffuse neutron scattering.”Physica B: Condensed Matter 335 (1 - 4), 157 -163. https://doi.org/10.1016/S0921-4526(03)00229-1[3] Schweika, W., Easton, S., & Neumann, K. U. (2005). “Vector Polarization Analysis on DNS”. NeutronNews, 16(2), 14-17. https://doi.org/10.1080/10448630500454262
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