Jean Witz (now deceased) once told me that the following paper is the first one mentionning data "collection" on a synchrotron. The journal is not really "obscure" and the paper should easily be found. The work was done in Germany, if I remember well.
G. Rosenbaum, K.C. Holmes and J. Witz, Synchrotron radiation as a source for X-ray diffraction, Nature, 230, 434-437 (1971). Philippe Dumas
