High-resolution focusing SANS with a toroidal neutron mirror

Abstract Presently, high-resolution instruments for small-angle neutron scattering (SANS) use the conventional pinhole cameras. For high resolution they have to be extremely long (80 m for D11). Much shorter instruments can be built with focusing mirrors [1–3]. So far, however, this principle was not successful because of the insufficient quality of conventional optical mirrors. Recently, we succeeded in building a 20 m long focusing instrument at the NSE spectrometer IN15 in the ILL Grenoble. It uses a 4 m long, high-quality mirror as developed for X-ray telescopes. The image has a sufficiently low parasitic halo. Test experiments on polymeric precipitates down to Q=4×10 −4 A −1 were successfully carried out. We expect that the Q -range can be extended to ≈10 −4 A −1 .