Number 199 (Story #4), October 19, 1994 by Phillip F. Schewe and Ben Stein THE EUROPEAN SYNCHROTRON RADIATION FACILITY (ESRF) , now in operation, is the brightest laboratory source of x rays. The $600 million machine, hosting about 2500 scientists per year, generates its x rays using a circulating beam of 6-GeV electrons. A 7-GeV machine at Argonne and an 8-GeV machine in Japan are currently under construction. (Science, 7 Oct.)