GENEVA - A 43-foot-long magnet for the world's largest particle collider broke "with a loud bang and a cloud of dust" during a high-pressure test, and officials said Tuesday they are working to find a replacement part. The part that failed March 27 was in a super-cooled magnet designed to focus streams of protons so that they collide and allow scientists to study the results of the collision, giving them a better understanding of the makeup of matter, according to Fermilab, based in suburban Chicago, which has an accelerator of its own and is helping build one deep beneath the...