PANDA Poly Axis Neutron Depolarisation Analyser

General description

The instrument PANDA has been designed to perform 3-dimensional neutron depolarization measurements. In these experiments the polarization dependent transmission of a monochromatic neutron beam is measured for three perpendicular polarization directions of the incident and transmitted neutron beam. This polarization dependent transmission can be expressed in a (3×3) depolarization matrix, which contains direct information on (1) the mean magnetic induction <B> and (2) the mean variation in the magnetic induction <(DB)2>. These variables can be analyzed in terms of the mean magnetization, the mean magnetic correlation length along the neutron beam, and the magnetic anisotropy when the general characteristics of the system are known.

 

Applications

  • Static and dynamic domain structures (100 nm to 30 um)
  • Magnetic phase transitions (measurement times down to 2 seconds)
  • Ferrofluids
  • Spin glasses
  • Magnetic recording materials
  • Flux line distributions in superconductors
  • Phase transformations in steel
  • Particle rotations in granular materials

P. Polarizer
D. Polarization rotator
S. Field-shielded sample box
A. Analyzer
Det. Detector

Instrument details

Neutron beam
Monochromator
Incident wavelength
Spread in wavelength
Degree of polarization
Neutron flux at sample
Polarizer& Analyzer multichannel
Polarization rotator
Detector
Time resolution
Sample table

2.5×5 cm2
pyrolytic graphite (200)
l = 2.03(2) Å
Dl/l = 2%
98%
5×104 cm-2s-1
CoFeV/TiZr mirror
coil system with 0.5% accuracy
3He counter
10 µs
automatic translation and rotation

Equipment

He cryostat
Furnace
Electromagnet

T = 2.5 - 300 K
T = 300 - 1100 K (dT/dt = 25 K/s)
B = 0 - 1.5 T

Transnational Access

This instrument can be used with European funding.

Literature on 3D neutron depolarisation

[1] M.Th. Rekveldt, Z. Physik 259 (1973) 391 [2] R. Rosman et al., Z. Physik B 79 (1990) 61; 81 (1990) 149.

[3] M.Th. Rekveldt, Transmission of polarised neutrons in magnetic materials, Physica B 267-268 (1999) 60.

 

 

Name author: M. Blaauw
© 2017 TU Delft

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