LIVERMORE, California, June 11 -- The U.S. Department of Energy Lawrence Livermore National Laboratory issued the following news: * * * Meet the machines that matter: the portable neutron detector Nuclear materials are rarely quiet. Even when hidden inside a sealed container, they emit a kind of heartbeat through streams of particles and radiation that carry critical information about its contents. In a laboratory, scientists have the tools and expertise to read that heartbeat. But in an eme  more