THE FIRST NEUTRON INTERFEROMETER BUILT OF HOLOGRAPHIC GRATINGS

Holographic gratings in thick slabs of photosensitised poly(methyl met hacrylate) are produced by illumination with UV interference fringes. The resulting modulation of neutron scattering length density makes th e gratings act as neutron beam splitters, a diffraction efficiency eta > 70% of the incident neutrons was achieved. An LLL-interferometer wa s built of three such highly efficient gratings, which had been adjust ed during their recording once for ever. The successful test with cold neutrons (lambda = 1.5 nm) revealed a degree of coherence of gamma ap proximate to 0.7.