The SLAC National Accelerator Laboratory, in Menlo Park, California, has a 3-kilometre-long electron accelerator. Credit: Matt Beardsley/SLAC National Accelerator Laboratory An X-ray laser, upgraded to become the most powerful in the world, produced its first beams on 12 September. Located in Menlo Park, California, the laser will produce one million X-ray pulses per second when running at full capacity. Scientists are excited to get a crack at the instrument, called LCLS-II, which w...