Development of new small-angle neutron scattering geometry with ring-shaped collimated beam for compact neutron source

Small-angle neutron scattering (SANS) is an important tool to investigate material properties in nanometer to micrometer scale. The opportunity to conduct SANS experiments is, however, limited because of the low number of available SANS beam lines. Compact neutron sources are expected to play a significant role to increase neutron scattering facilities including SANS beam lines. The problem is that the flux of compact neutron sources can be very low, which makes it difficult to measure scattered neutrons from a sample. A SANS geometry with ring-shaped collimated beam (r-SANS) is developed to conduct SANS experiments at very low flux neutron sources. By using ring-shaped collimated neutrons to hit a large sample, the scattered neutron flux becomes high on the ring center line because the scattered neutrons with each scattered angle overlaps on each point of the ring center line. By setting a 3He point detector on the center line and shielding the surrounding of the small detection area well, high signal to noise ratio experiments are possible. In this paper, we show the concept of this new geometry and a preliminary experimental result of a glassy carbon sample taken with the r-SANS geometry constructed at Kyoto University proton Accelerator Neutron Source (KUANS)