High-resolution focusing SANS with a toroidal neutron mirror

Presently, high-resolution instruments for small-angle neutron scattering (SANS) use the conventional pinhole cameras. Far 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=4x10(-4) Angstrom(-1) were successfully carried out. We expect that the Q-range can be extended to approximate to 10(-4) Angstrom(-1).