Number 47 (Story #4), September 13, 1991 by Phillip F. Schewe and Ben Stein THE COLD NEUTRON RESEARCH FACILITY , a source of cold (energies less than 5 meV) neutrons at NIST, has begun operation. Neutron beams, although not as intense as x-ray beams, are better than x rays for probing certain properties of matter, such as magnetic structure. Cold neutrons, with wavelengths of 4 angstroms or more, are useful for resolving mesoscopic structures (hundreds or thousands of angstroms in size) that are pertinent to the study of polymers, composites, and thin-film interfaces. The CNRF provides a home for cold-neutron researchers in the U.S. who for some time had had to make the trip to Grenoble, France, home of the Institute Laue-Langevin; ILL is currently shut down for an indefinite period. (Physics Today, Sept 1991.)