Abstract

0k0 n-beam diffraction patterns of germanium have been recorded by rotation of specimens about the diffraction vectors of the vanishingly weak 020 and 060, and the very strong 040 reflections. N-beam interactions were displayed clearly in the 020 and 060 scans, and somewhat less clearly in the 040 scan. Unambiguous phase indications, however, were detected only in the 040 scan. The experiments demonstrate that the visibility of n-beam interactions does not necessarily imply a corresponding visibility of experimental phase indications. The geometry of some unusual four- and five-beam interactions detected in the 0k0 scans, and the phases shown by those interactions, are also discussed.