SANS-1

View into SANS-1

Helmholtz-Zentrum Hereon designed and built the new small-angle scattering instrument SANS-1 at FRM II in co-operation with Technische Universität München.

The instrument is linked to the cold source of FRM II by an s-shaped neutron guide which lifts the beam height from ~ 1.2 m to ~ 1.5 m over the floor and acts as a strong filter of fast neutrons and hard X-rays from the reactor. At the exit of the neutron guide, velocity selectors with resolutions of 10% and 5% are available for monochromatizing the neutron beam with a maximum size of 50 mm × 50 mm.

Covering a length of 20 m, the collimator offers different options of setting the primary beam with high or low divergence for analysing samples in classical transmission or in grazing incidence geometry.

Around the sample position, free space over a length of ~ 3 m in beam direction can be made available for using different sample environments. All components in this area are made of non magnetic materials for the use of superconducting magnets. SANS-1 at MLZ

Instruments in the Neutron Guide Hall at the FRM II

A 2D-position sensitive detector with an active area of 1 m × 1 m and a position resolution of ~ 8 mm × 8 mm made of an array of position sensitive detector tubes with a diameter of 8 mm can be set at distances from ~ 1 m to 20 m from the sample. Each tube allows a maximum count rate of more than 105/s resulting in a maximum global count rate of ~ 5 × 106/s. The centre of the detector can be moved horizontally by ~ 50 cm perpendicular to the beam direction and rotated around a vertical axis to cover areas of large scattering vectors.

Transmission polarizers in front of the collimation allow using all beam configurations optionally with polarized neutrons, and polarization analysis will be performed by means of 3He-filters. Due to being stationed at the high flux reactor FRM II, its design and its various components, SANS-1 at FRM II is one of the leading SANS instruments in the world.

For improving the time resolution of in situ investigations covering large areas of scattering vectors, a chopper device similar to that of REFSANS as well as a second 2D-detector can be integrated in SANS-1 in future.