Geneva, 25 November 2015. After the successful restart of the Large Hadron Collider and its first months of data taking with proton collisions at a new energy frontier, the LHC is moving to a new phase, with the first lead-ion collisions of season 2 at an energy about twice as high as that of any previous collider experiment. Following a period of intense activity to re-configure the LHC and its chain of accelerators for heavy ion beams, CERN1’s accelerator specialists put the beams into collision for the first time in the early morning of 17 November 2015 and ‘stable beams’ were declared at 10.59am today, marking the start of a one-month run with positively charged lead ions: lead atoms stripped of electrons. The four large LHC experiments will all take data over this campaign, including LHCb, which will record this kind of collision for the first time. Colliding lead ions allows the LHC experiments to study a state of matter that existed shortly after the big bang, reaching a temperature of several trillion degrees.