Neutron polycapillary optics: present status and future trends

Up to present, neutron applications of polycapillary optics have been rather rear and mostly limited either to feasibility studies or to non-scattering techniques. The practical use of polycapillary focusing neutron optics for purposes of neutron scattering have been hindered by a serious degradation of momentum resolution caused by increased divergence of focused beams. However, limited size of samples available for research as well as limited brightness of present day neutron sources (both reactors and spallation sources) requires to rethink the current situation. Neutron lenses are successfully tested for low Q-resolution applications providing an enormous increase of neutron flux at small samples. Moreover, some recent developments in the field of neutron instrumentation allow us to overcome the resolution problem by decoupling the angular resolution and the incident beam divergence thus opening the opportunity for the use of focusing neutron optics in some high Q-resolution application. Further advances in technology required to improve the performance of neutron polycapillary optics, also in combination with modem methods of polarization of neutron beams, are discussed.