A comparison of different methods for improving flux and resolution on SANS instruments

Small-angle neutron scattering (SANS) is one of the most popular and oversubscribed techniques at every user facility for neutron scattering studies of condensed matter that offers it. The limiting features in SANS experiment design are the length of time required to make a measurement and the minimum momentum transfer Q that can be measured, and the resolution. In the traditional pinhole-camera geometry, these two constraints are inextricably linked, forcing tradeoffs. However, a number of methods have been developed for reducing this linkage, thus allowing higher throughput while retaining high resolution and a low minimum Q. These methods include using multiple confocal pinhole apertures, lenses, and focusing mirrors. We compare and contrast these options and discuss their suitability for use on instruments at pulsed neutron sources.