Elliptic neutron guides—focusing on tiny samples

We have investigated the focusing properties of the prototype of a transportable elliptic neutron guide. We demonstrate that the elliptic guide allows to map a point-like neutron source in one focal point on a tiny spot in the other focal point. We also show that an elliptically tapered neutron guide increases the neutron flux density in the focal point by at least one order of magnitude compared to the flux density of the original neutron beam. This allows to use neutron beams more efficiently in experiments with small samples. We used the elliptic neutron guide to focus a several centimeters wide neutron beam on a tiny NiS2NiS2 sample with the dimensions 0.1mm3 and easily detected the ordered moment of this antiferromagnetic insulator. This suggests that many more small samples, in particular in high pressure experiments, can be studied with elliptic neutron guides.