Laue crystallographic orientation with a fixed detector

✍ Scribed by John S. Reid

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 880 KB
• Volume: 75
• Category: Article
• ISSN: 0010-4655
• DOI: 10.1016/0010-4655(93)90177-e

✦ Synopsis

A FORTRAN program is described that finds the orientation matrix appropriate for a single crystal mounted on a Eulerian cradle in a Laue scattering apparatus where there is a fixed narrow aperture detector or fixed reference direction in the scattering plane. The essence of the alignment strategy is that two or more Laue spots are directed successively towards the reference direction, missing it by measured amounts. The program also evaluates the Eulerian angles x and 4' necessary to make a given reciprocal lattice plane the scattering plane, and evaluates the w angles necessary to direct reflections in the chosen scattering plane into the counter. The input data required are the lattice parameters of the sample crystal (or, with a variant, reference reflection wavelengths) and the Eulerian angles for two or more reflections that pass close to, but not necessarily directly into, the detector or reference direction. If angles for four or more reflections are available, zero errors in the Eulerian angles x and 4, are evaluated. Use is made of the NAg numerical subroutine library. A summary is included of the underlying algebra employed.