Solid state neutron polarisers and collimators

In most cases, neutron optical elements like polarisers or collimators use coated surfaces which define the neutron flight path in air or vacuum. To reduce the size of such elements silicon single crystals can be used as the medium in which the neutrons travel. We have built and tested a neutron polarising bender which consists of a stack of thin silicon wafers. The neutrons enter at the front side. Inside the wafers the spin up component is reflected from the supermirror coated side and can leave the wafers while the spin down component passes the supermirror and is absorbed in the Gd layer of the adjacent wafer. Other neutron optical element, we tested for the first time are several collimators made from silicon wafers coated with either Gd or reflecting coatings below an absorbing Gd layer. These collimators produce a beam with quasi-rectangular distribution of angles, which represents an intensity gain at equal resolution compared to the triangular distribution in conventional Soller collimators. Finally, we report on the first test of a solid state radial collimator. Some general aspects of sold state neutron optical elements are also discussed.