MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich

MLZ (eng)

85748 Garching


Polarized hot neutron diffractometer


POLI is a versatile two axes single crystal diffractometer mostly dedicated to the investigation of magnetic structures in single crystals using neutron spin polarisation. The using of the separate non-polarising variably focussing monochromators and optimised polarisers allows the structural investigations using polarised and non-polarised neutrons with short wave length and high resolution. Two standard options are currently implemented on POLI:

  • Zero-field spherical neutron polarimetry (SNP) using third generation polarimeter CRYOPAD;
  • Non-polarised diffraction under special conditions e.g. very low temperatures (< 3 K), magnetic and electric fields, high pressures, high temperatures, etc. using dedicated sample environments and out-of-plane lifting counter.

A third measurement method named flipping-ratio is under development and planned to be operational using a new 8 T magnet in 2016.

SNP allows distinguishing between the depolarisation and polarisation rotation occurring during the scattering in the sample. X, Y, Z components of the scattered polarisation are measured for each orientation of the incoming polarisation and hence a polarisation matrix of 9 elements for an individual Bragg reflection can be found. Determining the relationship between the directions of incident and scattered polarisations gives access to the 16 independent correlation functions involved in the most general nuclear and magnetic scattering processes. Generally, this leads to the direction’s determination of the magnetic interaction vector of magnetic structures. For those structures coinciding nuclear and magnetic reflections in reciprocal space, SNP leads to the amplitude’s determination of the magnetic interaction vectors, and hence to the magnetisation distribution. SNP could also be employed to study the magnetic domain distribution.

Actually, polarised 3He spin filters are used on POLI in order to produce and to analyse neutron polarisation. This method offers best performance in the polarising of hot neutrons. Tuning the pressure of 3He in the filter cell it is possible to optimise the polariser’s performance depending on wave length or experimental needs. The automatic correction of the time-dependent polarisation is applied. Because of the 3He filters’ sensitivity about non-homogeneous magnetic fields, a dedicated solid state supermirror bender will be used in the future for experiments with high magnetic fields.

Typical Applications
  • Complex commensurate and incommensurate magnetic structures studied in ground state (zero-field) – very useful especially for superconductors.
  • Studies of magnetic or magneto-electric domains using SNP on samples cooled in zero-field as well as in external magnetic field (up to 7.5 T).
  • The combination of magnetic and electric fields applied on the sample – important for the studies on multiferroic materials.
  • Determination of magnetic form factors (sometimes also in antiferromagnets).
  • Structural and magnetic phase transitions, phase diagrams.
Sample Environment
  • Standard closed-cycle cryostat (4 K – 425 K)
  • Variox LHe cryostat (1.5 – 300 K)
  • Lower temperature inserts on request
  • 2.2 T HTS magnet / 7.5 T magnet on request
  • 8 T dedicated magnet planned from 2016
  • Electric field up to 10 kV
Technical Data

Primary beam: SR-9a on hot source

  • Focussing monochromators
Cu (220)0.554·1060.92.4·107
Si (311)0.77·1061.152.8·107

Neutron polarisation: 3He spin filter

  • 3He polarisation: 0.75 – 0.7
  • Neutron polarisation: 0.93 – 0.8
  • Cell holding time: 2 days
  • Cells replacement time: 5 – 10 min

Diffractometer angles

with Cryopadwithout Cryopad
-10° < 2θ < 120°-30° < 2θ < 130°
-180° < ω < 180°-180° < ω < 180°
-4° < ξ1 < 4°-5° < ξ1 < 5°
-4° < ξ2 < 4°-5° < ξ2 < 5°
v = 0-4.2° < v < 30°

Cryopad (zero-field polarimeter)

  • Precision in polarisation control: better 1°
  • Low background / low absorption
  • LHe autonomy: 10 days
  • LN2 refill (automatic): daily
  • Space for closed cycle cryostat or orange type cryostat

Instrument Scientists

Dr. Vladimir Hutanu
Phone: +49 (0)89 289-12153

Dr. Hao Deng
Phone: +49 (0)89 289-54725

Phone: +49 (0)89 289-14480

Operated by



Find the latest publications regarding POLI in our publication database iMPULSE:

Citation of the instrument

Heinz Maier-Leibnitz Zentrum. (2015). POLI: Polarised hot neutron diffractometer. Journal of large-scale research facilities, 1, A16.

For citation please always include the DOI.



Instrument POLI with SNP setup.

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich