Peter Ginter/ATLAS collaboration/CERN

The Large Hadron Collider(LHC) in Geneva has collided heavy nuclei at the highest energies ever recorded.

The energy of the lead ion collisions currently taking place at Cern are twice as high as that of any other previous collider experiment. The collisions will take place for the next month, and involves positively charged lead ions -- lead atoms stripped of electrons.


The experiment will allow researchers at Cern to study the properties of systems interacting at high densities, giving us a better understanding of the state of matter that existed immediately after the Big Bang.

Increasing the energy of the collisions will increase the volume and temperature of what is referred to as the 'quark and gluon plasma'. Shortly after the Big Bang quarks (which Cern describe as "fundamental bits of matter") and gluons (the 'glue' that sticks quarks together into protons and neutrons), were bound together extremely weakly in a 'soup' -- the quark and gluon plasma. Increasing the density and temperature of this plasma will allow researchers to understand the medium formed during lead-ion collisions. "There are many very dense and very hot questions to be addressed with the ion run for which our experiment was specifically designed and further improved during the shutdown," said ALICE collaboration spokesperson Paolo Giubellino.

Lead ions collide in the CMS detector CERN


"For instance, we are eager to learn how the increase in energy will affect charmonium production, and to probe heavy flavour and jet quenching with higher statistics. The whole collaboration is enthusiastically preparing for a new journey of discovery."

The first collisions were recorded by detectors this morning and, although it is too early for a full analysis to be carried out, researchers said "the first collisions tell us that more than 30,000 particles can be created in every collision". "This is more than 40 times the energy density of a proton," according to Guibellino.

Researchers hope this new information will help them better understand the conditions in the universe up to a billionth of a second after the Big Bang. "It is a tradition to collide ions over one month every year as part of our diverse research programme at the LHC," said CERN Director-General Rolf Heuer. "This year however is special as we reach a new energy and will explore matter at an even earlier stage of our universe."