Buy article online - an online subscription or single-article purchase is required to access this article.
laboratory notes
A rigid highly symmetrical rectangular frame (physical symmetry mmm) can carry two goniometer heads coaxially, but opposed apex to apex; the frame itself is axially reversible. Used with monochromated synchrotron radiation, it permits quick inversion of crystal orientations by 180° rotations about the diffraction vector, as is required for comparison of lattice parameters in different parts of a single-crystal or between two separate crystals.