FISSION HELPS SUPERCONDUCTIVITY. One of the problems of using high temperature superconductors as wires in magnets is that the bundles of magnetic field lines that normally stay put in the presence of low currents start to move around (dissipating energy thereby) when larger currents are sent through the wire sample. Scientists working at Los Alamos have now used a proton beam to induce nuclear fission in mercury atoms in a mercury/copper oxide superconductor. The defects caused by the fissioning atoms splay out in all directions in the superconductor crystal and help to snag the wayward field lines. This permits the sample to carry much more current. (Nature, 18 Sept.)