Poster (After Call)

FZJ-2026-05279

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Polarized Neutron Diffractometer POLI at MLZ: Upgrades and Perspectives

Stödter, L. (Corresponding author)FZJ* ; Xu, J. ; Nyc, A.FZJ* ; Babcock, E.FZJ* ; Salhi, Z.FZJ* ; Soltner, H.FZJ* ; Pütz, J.FZJ* ; Ortmanns, T.FZJ* ; Schäfer, R.FZJ* ; Hanslik, R.FZJ* ; Staringer, S.FZJ* ; Thoma, H. ; Brandl, G.FZJ* ; Luberstetter, W. ; Hutanu, V. ; Mattauch, S.FZJ* ; Zobel, M.FZJ*

2026

Abstract: POLI is a hot neutron two-axis diffractometer at the Heinz Maier-Leibnitz Zentrum (MLZ), Germany, which uses spin-polarized neutrons for magnetic studies in particular. The instrument is used, for instance, to study complex magnetic structures, to reconstruct magnetization densities in the unit cell, and to explore phase diagrams of materials via multiparameter studies. To this end, three standard measurement setups are available reaching from unpolarized neutron diffraction under extreme sample conditions, over half-polarized diffraction to zero-field spherical neutron polarimetry (SNP). Here, we present recent developments of the instrument. The new in-situ 3He Spin-Exchange Optical Pumping (SEOP) polarizer and analyzer for POLI have been completed. With the return of neutrons at FRM II, they will provide a high level of constant neutron spin polarization during the polarized neutron diffraction experiments. To fully replace the previous Metastability Exchange Optical Pumping (MEOP) $^3$He polarizer and analyzer, two new nutators were manufactured for the SNP setup, which consist of rotatable, motor-driven stacks of Halbach magnets.

Keyword(s): Instrument and Method Development (1st) ; Magnetic Materials (1st) ; Condensed Matter Physics (2nd) ; Magnetism (2nd)

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Contributing Institute(s):

1. JCNS-4 (JCNS-4)
2. JCNS-3 (JCNS-3)
3. Heinz Maier-Leibnitz Zentrum (MLZ)
4. JCNS-FRM-II (JCNS-FRM-II)
5. Streumethoden (JCNS-2)
6. Institute of Technology and Engineering (ITE)

Research Program(s):

1. 6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ) (POF4-6G4) (POF4-6G4)
2. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)

Experiment(s):

1. POLI: Polarized hot neutron diffractometer (SR9a)

Appears in the scientific report 2026

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