Cold-neutron interferometer of the Jamin type

A cold-neutron interferometer using four independent multilayer mirrors is demonstrated. We have observed interference fringes with a contrast of 60%. The interferometer is based on a pair of devices using etalons with an air gap of 9.75 {mu}m in spacing. The optical system is equivalent to the Jamin-type interferometer, which allows much larger spatial separation between the two coherent beams than the previous type of multilayer interferometer to broaden the applicability of neutron interferometry.