ILL :: Neutrons for science : An example: the D22 polarizer

Optics

We provide neutron optical components for optimising neutron instruments. From monochromator and analyser crystals to converging guides, bandpass filters and polarising 3He spin-filters and supermirror devices, the ILL neutron optics lab provides the know-how and the in-house manufacturing capabilities. We develop and produce the neutron optical components required to maintain the leading role of the ILL in neutron scattering.

An example: the D22 polarizer

Polarizes neutron reflectivity of Fe/Si supermirror (9OO layers):

Measured in reflection geometry

600 μm thick silicon blade coated on both sides with m=4 supermirrors, placed in the collimating section with an incidence angle of 2°

Performance measurements on the instruments: C. Dewurst, S. Wood

=> at λ=10Å, 85% polarization and 44% transmission (of the unpolarized beam)

=> evaluation of the small-angle scattering contamination from the polarizer:

Parasitic peak (I_max/1000), at fixed position with λ (≠ off-specular scattering, origin ??).

But the polarizer will be placed before collimating section.

Direct beam profile measured with the polarizer placed at the sample position :

To top